Some Easy and some Extreme Techniques for Saving Fuel
Wayne Gerdes is the original and master hypermiler.
The following information is taken from his site: CleanMPG.com
Wayne was on KGO 810 talk radio on June 14, 2008. Listen here.
Wikipedia article: Hypermiler
Section I - What are the EPA City/Highway Tests?
Section II - Basic FE Techniques.
Section III - Advanced Hypermiling Techniques.
Table of Acronyms - I added this as the acronymic density got to me!
Section I - History and methods of the EPA’s Fuel Economy estimates
The EPA City/Highway fuel economy estimates are now 31 years young and were first implemented near the end of this nation’s first Oil crisis back in 1973/1974. The test(s) themselves were developed in 1972 to simulate a typical LA commute of that era.
EPA based Fuel economy is actually measured under controlled conditions in a laboratory using a standardized Federal Test Procedure (FTP) specified by federal law. Manufacturers test their own vehicles - usually pre-production prototypes - and report the results to EPA. EPA reviews the results and confirms about 10-15 percent of the total at their own National Vehicles and Fuel Emissions Laboratory.
In the laboratory, the vehicle's drive wheels are placed on a machine called a dynamometer that simulates the driving environment. The energy required to move the rollers can be adjusted to account for aerodynamic forces and the particular vehicle's weight.
On the dynamometer, a professional driver runs the vehicle through a standardized driving routine, or schedule, which simulates a “typical” trip in the city or on the highway. The City’s technical name is called FTP75 and the Highway’s test called the HWFET.
City Test (FTP75) represents urban driving, in which a vehicle is started with the engine cold and driven in stop-and-go rush hour traffic. The driving cycle for the test includes idling, and the vehicle averages about 20 mph.
City Test - Vehicle speed vs. time in seconds.
Highway Test (HWFET) represents a mixture of rural and interstate highway driving with a warmed-up engine, typical of longer trips in free-flowing traffic. Average test speed is about 48 mph and includes no intermediate stops or idling.
Highway Test - Vehicle speed vs. time in seconds.
High Speed Test represents a high speed highway driving cycle up to 80 mph and with higher acceleration rates of almost 3X’s that of the older FTP and HWFET cycles.
High Speed Test - Vehicle speed vs. time in seconds.
A/C High Temperature Test represents a light mixture of city stop and go and low speed highway driving but in 95 degree F temperatures with A/C on MAX.
High Temperature Test in 95 degree F temperatures - Vehicle speed vs. time in seconds.
City Test under Cold Temperatures represents the exact driving schedule as the FTP75 above but with temperatures of 20 degrees F vs. 68 - 86 degrees F and with the Engine temperature cold soaked before start.
City Test in 20 degree F temperatures - Vehicle speed vs. time in seconds.
In the early 1980s, an EPA study found that drivers were typically achieving lower fuel economy than predicted by EPA laboratory tests. As a result, EPA required the laboratory-derived city and highway MPG estimates posted on the labels of new vehicles to be adjusted downward by 10% for city estimates and by 22% for highway estimates to better reflect the MPG real-world drivers could expect from 1985 through 2007. For 2008 looking forward, the 3 additional tests cycles will again help bring the estimates closer to real world for most if not all owners and their vehicles.
Fuel Economy Test Schedule Characteristics
|Driving Schedules Attributed||City||Highway||High Speed||AC||Cold Temp|
Trip Type||Low speeds in stop-and-go urban traffic||Free-flow traffic at highway speeds||Higher speeds; harder acceleration & braking||AC use under hot ambient conditions||City test w/ colder outside temperature|
Top Speed||56 mph||60 mph||80 mph||54.8 mph||56 mph|
Average Speed||20 mph||48 mph||48 mph||22 mph||20 mph|
Max acceleration||3.3 mph/sec||3.2 mph/sec||8.46 mph/sec||5.1 mph/sec||3.3 mph/sec|
Simulated Distance||11 miles||10 miles||8 miles||3.6 miles||11 miles|
Time||31 minutes||12.5 minutes||10 minutes||9.9 minutes||31 minutes|
Idling||18% of the time||None||7% of the time||19% of the time||18% of the time|
Engine Temp at Startup *||Cold||Warm||Warm||Warm||Cold|
Lab Temperature||68 - 86 degrees F||68 - 86 degrees F||68 - 86 degrees F||95 degrees F||20 degrees F|
Vehicle Air conditioning||Off||Off||Off||On||Off|
* A vehicle's engine doesn't reach maximum fuel efficiency until it is warm.
As most here understand, some of the FTP75 and HWFET test characteristics are almost unbelievable given what most of us here are used to driving in and through on a daily basis for any number of reasons. Despite the EPA’s attempt to Band Aid over some of these problems, the std. FTP75 and HWFET (pre-2008) fuel economy tests still suffer from several fundamental flaws, including the following:
- Underestimating highway speeds - The EPA highway cycle assumes an average speed of 48 mph and a top speed of 60 mph. Many state highway speed limits are set at or above 65 mph. Government data indicates that fuel economy can drop by 17% for modern vehicles that drive at 70 mph instead of 55 mph. Even at 65 mph, fuel economy can drop by nearly 10% compared to driving at 55 mph.
- Underestimating the severity of and amount of time spent in stop-and-go urban congestion - Congestion is getting worse. In 1982, congestion added about 7 hours per year to the average person’s annual travel, by 2001, congestion effects had nearly quadrupled to 26 hours per year. While EPA data shows that we spend about 62% of our time in urban driving, EPA still assumes only 55%.
- Assuming very gentle acceleration and braking - the maximum acceleration rate in the EPA test cycles is 3.3 mph per second, about the same as going from zero to 60 mph in about 18 seconds. The average new car or truck can accelerate nearly twice as fast. While most consumers don’t use all the power in their vehicle, EPA data shows that people accelerate as fast as 15 mph per second, nearly 5 times the EPA tests. In 1996 EPA established a new driving cycle (US06) that includes tougher acceleration and deceleration and higher speeds, but this cycle is not used for fuel economy purposes.
- Neglecting the wide range of outdoor temperatures experienced in the real world - The EPA tests are performed between 68 and 86 degrees Fahrenheit. Most states frequently experience weather conditions outside this range and fuel economy can be significantly affected as a result.
- Failing to reflect the use of air conditioning - Fuel economy tests are run with the air conditioning off, while over 99% of all cars and trucks come with air conditioning. In 1996 EPA established a new driving cycle (SC03) that included air conditioning, but this cycle is not used for fuel economy purposes.
- Overestimating trip lengths- The EPA city test cycle is 7.5 miles long. EPA’s own data, however, indicate that average trip lengths may be only 5 miles long, with typical trips as short as 2.5 miles. Shorter trips often mean lower fuel economy because the engine does not have time to warm up and operate efficiently.
- Ignoring advances in automotive technology - Over the past 20-30 years, vehicle technology has changed significantly and new technologies are continuing to enter the market. Many of the factors listed above affect vehicles with new technologies differently than they affect today’s conventional cars. Therefore, EPA’s 30 + year old test procedures and the concept of a new set of “adjustments” are even more ineffective for new technologies. This will make it difficult for anyone to compare a hybrid to a non-hybrid.
- Ignoring heavier vehicles - Fuel economy information is not required for nearly 6 million light duty trucks on the road today. These are SUVs, pickups, and vans rated above 8,500 pounds gross vehicle weight. A recent J. D. Power survey found that the top complaint with the Hummer H2 was its poor fuel economy - consumers just did not know what they were getting into. And if you are a farmer or small business owner who needs a big pickup, you are left in the dark.
With the above, you should have a better understanding of both the history and the problems associated with the past EPA city and highway fuel economy estimates. With the 3 new tests added for the 08 EPA test cycles and accompanying estimates looking forward, the new EPA numbers should place 90% of the driving public into a category that matches what they actually receive.
I am sure everyone here has read an article or two where the author or publication states hybrids do not receive anywhere near their EPA ratings. Given the above, does it surprise anyone that no other automobile does either? Some automobiles do better than others of course but overall, an individual car owner whose automobile is rated at an EPA combined of 25 MPG and receives 20% less from it at 20 MPG is in the exact same situation as that of a Prius II owner whose EPA combined is 55 (Pre 08 specs) and receives 44 MPG. Sound familiar? Individual #1 is missing the mark by just 5 mpg so it does not seem like a lot whereas the Prius II owner misses by the same percentage but 11 MPG less than 55 is a larger number but not a larger percentage. I hear the same thing all the time and all I can do is shake my head and wonder how these individuals can stand receiving just 20 MPG or less from whatever they are driving vs. the Prius II’s 44 if they were to drive without a care in the world. Because of an Insight’s, Prius I’s/II’s, HCH-I’s/II’s, and FEH’s built in Fuel Consumption Displays, we have a very distinct advantage over the EPA test(s) and the individual receiving just 20 MPG from his or her 25 MPG EPA rated automobile. We have a multitude of feedback instruments so as to adjust our driving habits to improve upon our results segment after segment, commute after commute, and/or tank after tank. Remember that if you were to take a brand new Prius II, HCH-II, or FEH and run it through the exact same accelerations, decelerations, stops, and starts in the same temperature band that the EPA city/highway tests dictate, you would receive almost exactly the same MPG as the EPA city/highway estimates posted on your cars when you first purchased them.
Section II - Basic FE saving techniques
Now that we have a good feel for what others perceive as a problem without knowing what they themselves are achieving, let us begin to consider the ways to match if not beat the EPA estimates.
Maintain your Automobile: A poorly tuned engine burns more fuel, so fuel economy will suffer if it is not in tune. Improperly aligned or under inflated tires can lower fuel economy, as can a dirty air filter or brake drag.
- Do not use quick accelerations or brake heavily: This reduces fuel economy by as much as 33 percent at highway speeds and 5 percent around town. EPA tests do not account for this kind of vigorous driving.
- Do not idle excessively: Decreases average FE. The EPA city test includes idling, but drivers that experience more idling experience lower MPG.
- Do not drive at higher speeds: This increases aerodynamic drag (wind resistance) and mechanical friction which reduces fuel economy. The EPA test accounts for aerodynamic drag up to highway speeds of 60 mph, but drivers often exceed this speed.
- Cold weather and frequent short trips reduce fuel economy, since your engine doesn't operate efficiently until it is warmed up. In colder weather, it takes longer for your engine to warm, and on short trips, your vehicle operates a smaller percentage of time at the desired temperature. Note: Letting your car idle to warm-up doesn't help your fuel economy, it actually uses more fuel and creates more pollution. Drive to your furthest destination first and then as you are heading home, stop at the closer destinations in order from furthest to closest as the car is warmed up for longer portions of your drive.
- Remove Cargo or cargo racks: Cargo and/or racks on top of your vehicle (e.g., cargo boxes, canoes, etc.) increase aerodynamic drag and lower FE. Vehicles are not tested with additional cargo on the exterior.
- Do not tow unless absolutely necessary: Towing a trailer or carrying excessive weight does decrease fuel economy. Vehicles are assumed to carry three hundred pounds of passengers and cargo in the EPA test cycles.
- Minimize running mechanical and electrical accessories: Running mechanical and electrical accessories (e.g., air conditioner) decreases fuel economy. Operating the air conditioner on "Max" can reduce MPG by roughly 5-25% compared to not using it.
- Avoid driving on hilly or mountainous terrain if possible: Driving hilly or mountainous terrain or on unpaved roads reduces fuel economy most of the time. The EPA test assumes vehicles operate over flat ground.
- Do not use 4-wheel drive if it is not needed. 4-Wheel drive reduces fuel economy. Four-wheel drive vehicles are tested in 2-wheel drive. Engaging all four wheels makes the engine work harder and increases crankcase losses.
Try to purchase high BTU content gasoline if available: Fuels Vary in Energy Content and some fuels contain less energy than others. Using oxygenated fuels or reformulated gasoline (RFG), can cause a small decrease (1-3%) in fuel economy. In addition, the energy content of gasoline varies from season to season. Typical summer conventional gasoline contains about 1.7% more energy than typical winter conventional gasoline.
Inherent Variations in Vehicles: Small variations in the way vehicles are manufactured and assembled can cause MPG variations among vehicles of the same make and model. Usually, differences are small, but a few drivers will see a marked deviation from the EPA estimates.
Engine Break-In: New vehicles will not obtain their optimal fuel economy until the engine has broken in. This may take 3-5 thousand miles.
Speed Destroys FE!
I want to bring to everyone’s attention actual Speed vs. FE data many here may not be familiar with in a number of high FE hybrid vehicles. With them, I believe you will see why it is so easy to achieve and exceed the FE posted on the side of your new car when cruising down the roadway.
Prius II (EPA city/highway: 60/51 mpg) Constant speed tests - MPG Results
Conditions: 73 degrees F - Tire pressures 47 psi - no A/C - 1.0 mile distance at steady state speed.
HCH-II (EPA city/highway: 49/51 mpg) - Constant speed tests - MPG Results
|With Cruise Control|| || |
Run #||50 mph||60 mph|
1||63.4 mpg||55.9 mpg|
2||74.5 mpg||65.3 mpg|
3||64.9 mpg||60.9 mpg|
|| || |
Averages||67.6 mpg||60.7 mpg|
Conditions: High 70 degree temps - Tire pressures 40 psi - no A/C - 1.0 mile distance at steady state speed.
Ford Escape Hybrid (EPA city/highway: 36/31 mpg) - Constant speed tests - MPG Results
|With Cruise Control|| || || || |
Run #||30 mph||40 mph||50 mph||60 mph|
1||84.3 mpg||89.3 mpg||69.1 mpg||56.4 mpg|
2||86.5 mpg||89.0 mpg||64.8 mpg||48.5 mpg|
3||85.1 mpg||90.7 mpg||67.3 mpg||50.5 mpg|
|| || || || |
Averages||85.3 mpg||89.7 mpg||67.1 mpg||51.8 mpg|
Conditions: Mid 90 degree temps - Tire pressures 52 psi - no A/C - 1.0 mile distance at steady state speed.
|With Cruise Control|| || || || |
Run #||30 mph||40 mph||50 mph||60 mph|
1||56.8 mpg||56.2 mpg||51.2 mpg||42.0 mpg|
2||62.3 mpg||56.0 mpg||51.8 mpg||42.5 mpg|
3||57.8 mpg||56.0 mpg||51.1 mpg||42.5 mpg|
|| || || || |
Averages||59.0 mpg||56.1 mpg||51.4 mpg||42.3 mpg|
The key here is that a well setup Prius II can achieve about 65 MPG between 50 and 60 mph, a setup HCH-II can achieve about 90 MPG between 30 and 40 mph, and a very well setup FEH can achieve almost 60 MPG between 30 and 40 mph just by using CC (Cruise Control)!
Section III - Advanced hypermiling techniques
Tire pressures are a very important key to higher fuel economy. The higher the pressure, the lower the rolling resistance, the higher the fuel economy. The absolute minimum you should use is the driver’s side door or owners manual recommended tire inflation criteria. This is what the EPA and your car manufacturer sets tire pressures to during the EPA city/highway testing. MAX sidewall is what I would recommend for most as it is well within the safety limits of your car and tire and allows better FE than the pressure listed in the driver’s side door. I can discuss but cannot personally recommend upwards of 25% higher than MAX sidewall as there are legal constraints we all have to live with. That being said, 50 + #’s leads to even higher FE. Pros, higher FE, lower tread wear, more even treadwear across the treads width, shorter braking distances in a variety of conditions, and in many cases, even better handling. Cons, higher NVH (Noise, Vibration, Harshness).
Oil types and amounts are another important key to higher FE . A proper amount of low kinematic viscosity oil can do wonders for not only longevity of your ICE but the FE your automobile may be capable of. You should use oil with a viscosity that is within the band of your automobiles lubrication requirements. That being said, not all oils are the same. If your automobile allows a 5W-20, you should be OK using a high quality Synthetic 0W-20. Mobil1 0W-20 has the lowest kinematic viscosity as well as superior wear and breakdown properties vs. ANY non-synthetic I know of. About that level … I recommend that instead of filling the case up to the high level mark that you instead use just enough oil to bring the level up to between the high and low marks. You lose capacity in case of a leak and have a very slight increase in oil temps but gain a slight amount of FE with a slightly lowered strain on the ICE’s frictional components.
Advanced Hypermiling Techniques
FAS: Forced Autostop in any vehicle: A Honda hybrid will AS (Autostop) in various scenarios although it is very limiting to a given condition. Too high a speed, too cold, not enough SoC (state of Charge), not enough speed since last AS, Defrost or A/C on except for the AH and HCH-II in specific conditions, etc. will not allow AS … Forcing an AS in any vehicle (other than an HSD equipped hybrid), aka FAS, takes these limits out of the equation. Shift to N, let the Tach stabilize, key back to IG-I (shuts down the ICE and electronics), key back to IG-II to reboot the electronics and coast to a stop or pre-determined lower speed depending on conditions. Recover by starting up ICE via key to IG-III, release to IG-II, and engage transmission with a rev match to continue on your way. Pros include a very noticeable increase in FE over any short distance trip and is required in a few areas of the US as well as much of Europe, ie. sitting at a stop sign for > 15 seconds or at a stop for > 5 minutes … Cons include powerless coast, power brake assist is lost after a few applications, power steering is lost although at speed, you do not need it, is illegal in some locales, and possibly both gear reduction starter wear from excessive ICE starts and pre-mature wear from re-engagements of the transmission at speed.
D-FAS: Draft-Assisted FAS: When approaching a proper point to invoke a FAS, a draft target can be selected to increase the glide distance on the back side of the FAS. You have a speed of 65 mph; a draft target is up ahead doing 57 mph. You invoke FAS and glide into the distance draft, then into the close-in, fall back into the distance, and fall back away into a naked Glide. Pros include extending Glide distances significantly thus increasing overall FE (Fuel Economy) if performed properly. Cons include having to use brakes if you came into the draft target too hot, a close-in draft is dangerous, and the wear issues included above.
P&G: Pulse and Glide - See the following article for more details: P&G plus Warp Stealth in the Prius II for maximum FE …
This technique used to increase the FE of any automobile under the right conditions significantly above your automobiles EPA city/highway rating. In a nutshell, it includes a FAS in many hybrid and non-hybrid automobiles to a lower target speed (some hybrids can be influenced into this mode of operation with the right application of multiple accelerator pedal inputs), reigniting the ICE, re-engagement of the Tranny with rev match, and re-acceleration to a higher target speed, repeat. Pros include maximizing FE in a low speed suburban or city environment (speed limits less than 45 mph). Cons include lowering your overall average speed (more time to get to point B), a lot of work given the undulations depending on the type of hybrid or non-hybrid you are driving, and both gear reduction starter and pre-mature transmission wear from re-engagements at speed depending on the automobile being analyzed.
: High Speed P&G: The P&G technique was originally created to pull extreme FE from the HSD and eCVT equipped hybrids (Toyota’s and Ford’s) below 41 mph. The HS-P&G technique is used for many Honda hybrids and all non-hybrids if their transmissions can be re-engaged at speed. Instead of a 39 - 32 mph std. P&G range (just an example), you can step up the speed range to 70 - 55 mph (another simple example). Pros are increasing FE depending on temperature, weather, traffic, and road terrain conditions. Cons include lower overall average speed, more work than any other technique other than the warm-up P&G, safety issues with a powerless Glide (see above), caveats in regards to different manufacturers if this is even possible or not … and when applied incorrectly, can actually lower your overall FE.
Warm up P&G
: Exactly as stated. During warm up, your automobiles FE is at its absolute worst (open loop ops, high RR (rolling mechanical resistances) in colder temps). To attempt to alleviate some of the FE hit, you begin P&G’ing almost immediately but at lower and increasing speed ranges. P&G speed ranges are significantly reduced and stepped up as you arrive to higher speed arterials, state routes, and then Interstates and highways. Here is just one example as you are leaving your home via the subdivision or local street when conditions allow … A range example could include 0 - 15 mph, FAS to 10, 10 - 20 mph, FAS to 15, 15 - 30 mph, FAS to 20, 20 - 40 mph, FAS to 30, 30 - 50 mph, FAS to 40 … Again, this was just 1 example of what may be performed under a specialized local driving condition and temps until the automobile in question is up to full temperature. Pros include alleviating the warm up FE hit to far above what would normally be possible and help to maintain your overall FE even though you are in effect warming up the car. Cons include the most work of any technique posted so far, a lot of wear on a cold ICE, lengthier warm up time, and in some cases, more emissions due to the NOx spike on multiple re-ignitions. All other ICE-Off caveats also apply.
: Driving w/ Load: Instead of relying on CC (Cruise Control) to maintain speed, you rely on your iFCD (Instantaneous Fuel Consumption Display) and accelerator pedal for those automobiles that have them to stay locked in at a given fuel economy. One example would be when climbing an overpass. Instead of holding a steady speed up, over, and down the other side, you allow speed to drop as you climb while maintaining load or FE on the ICE and climb back to initial target after the decline on the backside. Begin the overpass climb at 65 mph, drop off speed as you climb, reach 62 mph at the crest, increase speed on the decline back to 65 mph. The technique depends on elevation deltas and traffic conditions. This can be simulated in a non iFCD equipped Accord or other automobile by locking in the accelerator pedal when approaching the overpass. Just hold the accelerator steady into, up, over, and down the back side at the same exact angle while arriving at the same initial target speed after the overpass has been cleared. There are slight accelerator pedal changes that can maximize the technique for those with iFCD’s but the locked down accelerator will work well for those just starting out and with a lack of an iFCD. An even easier way to understand the technique is to drive like a roller coaster coasts over the peaks and through the troughs. Pros are increased FE over any small terrain delta with a minimum of work. Cons are that there is thought and user input involved as well as slightly lowering your overall average speed to a given Point B.
: Driving w/out Brakes (or Driving w/ Buffers): In its simplest form, you drive as if you do not have brakes. If you have degraded or no brakes for whatever reason, you will increase buffers in traffic like you may never have considered previously. In heavy traffic and traffic jam conditions, this will allow you to maintain some speed before throwing away energy to heating up the pads/shoes. With larger buffers comes the ability to maintain a very slow speed while most others are in a stop and go jam. You can use this in any traffic tie up or heavy congestion. Pros include higher FE, less wear on the ICE and braking systems, and easier on your mental state. Cons include drivers near may continuously fill your buffers and thus you will again back off to recreate them. It may actually tax your mental state depending on your aggressiveness.
: Potential Parking: When entering a parking lot of any description, seek out the highest spot in said parking area. What this encompasses is looking for the highest elevation (Potential) and usually FAS’ing to bleed off speed so you DWB into said spot. On egress, you have a downhill slope to help you accelerate in a FAS or with ICE-On thus increasing your overall average FE. Pros, decreased fuel consumption and usually easier egress as you are usually in the back of the mall, grocery store, whatever. Cons, usually farther from the store entrance and thus a longer walk.
: As described. When parked, you want your egress to be as clean as possible. Instead of ICE-On, Reverse, Brake, Drive, pull forward, you pull in to whatever parking lot, area, Face-Out. What it does is eliminate Reverse or any unintended fuel use to spin around. Some can use this technique even from their home with limited or no fuel consumption with a FAS based turn around Face-Out. If your drive allows (mine does) you are in a FAS coming into your drive, pull into the highest spot, coast back while spinning the car around 180 degrees to a slightly lower spot. You are now Face-Out for your next days or drives egress. Even if you do not FAS, it is best to spin your car around when it is already warmed up than in the morning from dead cold. Your fuel consumption at dead cold is much higher than when warm. Pros, lower fuel consumption. Cons, you have to be careful that someone would not pull in behind and limit your ability to load your trunk.
Three Lights out or distant anticipatory focus
: When driving in any environment, continuously scan the road far ahead looking for situations or obstacles which may impede your steady state progress. In the heavier suburban or city environment, I recommend looking ahead 3 lights. Not only will this give you an advantage of light timing but you will also have a much heightened awareness of the traffic and terrain conditions ahead, to the side, and even behind!
: Assume a stop light ½ a mile ahead. You see Stale Green (Green for a very long time ready to turn Yellow) or already red and will not change until a car comes up upon it and trips the sensors in the pavement to change it back to green. You want to have any traffic around you (the Rabbit) trip the weight sensor before you are anywhere near that light so you are unimpeded with a green light by the time you reach it.
: If you have a choice between a 65 mph limited high speed route w/ few lights to work or a 40 mph limited route with some lights to work, which one do you take? The 40 mph limited route will give you many more opportunities to achieve FE far above the EPA ratings of your hybrid as seen in the speed tests above. The techniques you can use to maximize FE by P&G or FAS are just 2 examples of many.
Prius II “Warp-Stealth”
- Incline: When coming to a red light or stop sign on an incline heading upwards, you want to travel as far up the hill or ascent as possible before stopping. Starting from a dead stop while facing an uphill climb is the absolute worst FE scenario imaginable. SB on an incline can help reduce the FE hit if performed properly.
- Descent: When coming to a red light on a descent, you want to stop well before the actual light or traffic ahead so as to use the potential still available to help you accelerate back up to speed through the light. There will have to be at least one car well out in front in the case of weight sensored lights so as to trip them for you so you can glide/coast down the incline and possibly across the intersection before having to restart your car for propulsion again.
- Slowing for/with traffic or traffic signals: Have ever heard that if you move half the distance to the goal line again and again you will never reach said goal line? The same can be said for your speed when coming to a stop. What you want to attempt is to continue slowing before you actually stop until the light changes to green and you can re-accelerate without having to do so from a stop.
: See the following article for more details: P&G plus Warp Stealth in the Prius II for maximum FE …
It is used to minimize regen drag while slowing in the Prius II from highway speeds above 41 mph or more. You can place the Prius II into what is called warp stealth in this scenario. This takes the ICE off-line, and removes all Regen so as to extend your glide distances with little amp draw from the pack. The only difference between the “Glide” portion of “P&G” and “Warp Stealth” is WS is achieved above 41 mph and draws off the pack a small amount whereas “Glide” draws little to nothing off the pack below 41 mph.
: See Tarabell’s Adapting Basic Hypermiling Techniques to the HCH-II
article for more details. You want to let off the accelerator just enough to induce Regen, ICE injectors and intake/exhaust valves close, then re-apply just enough accelerator to remove your Charge bars and you are in an almost coast free state. The ICE is still turning over but you are using no fuel and your pumping losses by moving air through the ICE are at an absolute minimum.
: See Tarabell’s Adapting Basic Hypermiling Techniques to the HCH-II
article again for more details. After “Gliding” to your lower speed target, you slowly add accelerator pedal to bring on the pack to help provide propulsion. Again, no fuel burn and you can ride the pack under EV for some ways.
FEH “LGA to N (Low Gear Advantage to Neutral) on tach bounce and to D (Drive)”
: See Gary G’s Hypermiling the Ford Escape Hybrid ...
article for more details. While traveling on a 40 mph or less limited roadway, you place the gear selector in L at any speed at or below 43 mph, induce a small amount of regen, reapply accelerator just enough to remove regen and you should see the tach “Bounce” off of 1,000 RPM. At this point, the ICE is going to shut off and you can shift to N for the longest “Glide” to a lower target speed. Once the lower target speed is reached, place the gear selector back into D and EV until you are ready for the ICE to start back up and recharge the battery if need or need to accelerate well beyond 40 mph for higher speed travel.
: Ridge Riding. In inclement weather, you ride the center and white line edges to alleviate some of the drag caused during rain and/or wet conditions. In most cases during rain, the center crown or ridge will have the least depth of water to plow though as will the right or left edges of your lane. You can see the changing depths ahead and adjust your track as conditions change/allow. You want to ride the ridges whenever conditions make it possible to do so. In the snow, you will generally want to ride the most traveled tracks as they may be clear of snow, slush, water vs. riding the lanes with a snow cover or accumulation. Pros, maximizes FE in the worst conditions. Cons, requires quite a bit of concentration to maintain the wheels within a tight area of roadway. What I would like most here to use RR for is the safety aspect. RR helps wake up drivers behind you as you appear far different just by your placement on the road than anyone they may have encountered today. This “Wake Up” places them into a more defensive driving mode which is only to your benefit as they pull around to pass if traveling above the limits far sooner than they may have if you were not RR.
Close in Draft
- Close-in: Pulling into < 1.0 seconds directly behind a semi-tractor trailer rig at speed. Results can be astounding but with severe consequences as the probability of an accident increases at a higher rate than does your FE so it is not recommended! Doubling the EPA over a short time period is doable under the right circumstances.
- Distant: Pulling into > 1.0 seconds directly behind a semi-tractor trailer rig at speed. Results good as there is slightly less wind drag to break as well as being much safer than a Close-in.
- Surf: Pulling in just behind and along side of semi-tractor trailer rig at speed attempting to reduce your own aerodynamic drag by riding in the broader wake the rig ahead and to the side of you has created. Results are minimal but better than driving naked into the wind.
- Traffic Side: Traveling at a slower speed in the far right lane while traffic passing creates a bow wake effect across the entire highway/road in which you are traveling. Results are excellent the heavier the congestion is as long as there is some speed difference between you in the far right lanes and the traffic in the left lane(s) as you are receiving both the high FE from the slower speeds as seen in the steady state speed tests above as well as receiving a lowered aerodynamic drag because of the wake helping to pull you along.
So what do you do with all this entire list of techniques? What we are attempting to achieve is changing the EPA’s 11 mile city test so as to travel the same 11 miles but under our constraints, not theirs. The EPA test has you come to 23 complete stops. We are going to try and achieve 0 stops over those same 11 miles! In the highway test, we are using a far superior setup and DWL within DWB to achieve greater than the EPA highway test across its 10 mile distance. In other words, we are changing the rules of the City and Highway test to match our own much higher FE goals, not the EPA’s lowly ones!
Each of the techniques above has a risk reward basis to them. If you do attempt to use any of the above techniques, I would very much like you to try them one at a time on a relatively desolate roadway so as to cause the least amount of impact to others while learning and practicing. Once the new technique has become completely second nature, then and only then should you begin to become acquainted to the next technique. After all the tools are understood, practiced, and have become second nature, you can use those that are applicable to a particular automobile for a given traffic condition to maximize your own FE.
Whether you choose to use some or all of them in combination during a particular driving condition is up to you but if you do use what is applicable to your particular automobile in a given speed range in a given traffic condition, beating the EPA is a relatively easy thing to achieve and the actual results will literally astound you as you will see below!
Honda Insight - Sustained 150 + mpg
Honda Civic iCDTi - Sustained 135 + mpg
Prius II - Sustained 100 + mpg
HCH-II - Sustained 100 + mpg
And one of my favorites, the Ford Escape Hybrid SUV. Not only is this an extremely capable mid-sized SUV, it can achieve FE most would not have believed just 2 years ago using some of the exact techniques presented above.
FEH - Sustained 70 + mpg
This is a working document with even more to be added in the very near future. Stay tuned If you would like to copy excerpts, please link back to the original article if at all possible. Thanks to everyone involved with high FE for making this possible.
|BTU||British Thermal Unit|
|CVT||Continuously Variable Transmission|
|D-FAS||Draft Assisted Forced AutoStop|
|DWB||Driving Without Brakes|
|DWL||Driving With Load|
|eCVT||Electronically controlled Continuously Variable Transmission|
|EPA||Environmental Protection Agency|
|FEH||Ford Escape Hybrid|
|FSP||Fuel Sucking Pigs|
|FTP||Federal Test Procedure|
|HCH||Honda Civic Hybrid|
|HS-P&G||High Speed Pulse and Glide|
|HSD||Hybrid Synergy Drive|
|HWFET||Highway Fuel Efficiency Test|
|ICE||Internal Combustion Engine|
|iCDTi CI-ICE||European Honda Diesel - internal combustion diesel turbo i(?) Compression Ignited - Internal Combustion Engine|
|iFCD||instantaneous Fuel Consumption Display|
|IG||Ignition - positions|
|IMA||Integrated Motor Assist|
|MPG||Miles Per Gallon|
|MPH||Mile Per Hour|
|NVH||Noise, Vibration, Harshness|
|P&G||Pulse and Glide|
|PSI||Pounds per Square Inch|
|RPM||Revolutions Per Minute|
|RR||Rolling Resistance (of tires)|
|SUV||Sports Utility Vehicle|
|SoC||State of Charge|