Free Fuel!
Remember the phrase "Your Mileage May Vary?" Well, it's more true than you think. Because it usually averages out over a 300 mile tank, most people have no idea how wildly their mileage varies while they're driving. The trick is to consistently identify and limit the situations that get the worst mileage and maximize the situations that get the best mileage.With only a little practice, I was able to permanently improve my average by over 30% over the course of a few weeks. It was like getting a free tank of gas every month! In the first year of adopting these techniques, I saved 150 gallons of fuel and about $500.
You don't have to drive like a grandma (or a jerk) to accomplish this. The media have devoted a lot of negative coverage lately to extreme fuel-economy techniques. Don't believe the hype. You can get fantastic mileage without doing anything dangerous or stupid. You just have to learn what helps your fuel economy and what hurts it.
Hybrids are great, but it's more cost effective to learn to learn to drive efficiently before spending thousands or making other big changes to accomodate a more fuel efficient vehicle in your life.
Here's a short list of the basic techniques that anyone can do to save fuel. Click on any of the underlined words to link to the more detailed explanations below:
How To Do It
The Basics | Next Steps | Equipment | How Not to Do itIn addition to equipment choices that can affect your mileage, there are techniques you can adopt that target and minimize specific situations in which fuel is typically wasted. Some are easier than others. Some cost money and others are free. You don't need to drive a hybrid, and you can do this without doing anything that is unsafe, bad for your car or illegal!
Air up! |
The tire pressure indicated on your car's door jamb is recommended by the automaker for comfort and is minimum, not a maximum. The maximum pressure (usually 44psi) is stamped on your tire sidewall.
Inflating your tires to this pressure when cold is not overinflation, will not cause premature wear, actually reduces your risk of blowouts, and will save you 5-10% on the highway. There is an enormous safety margin built into this pressure rating, and your tires are designed to be run under a full load at this pressure! |
Savings: Medium. Cost: Up to 75 cents. Difficulty: Easy. |
Ease up! |
Speeding costs you more in fuel than it saves you in time. Above 60 mph, a 10 mph jump in speed increases wind resistance by over a third and costs you 20% more fuel.
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Savings: Huge. Cost: Free. Difficulty: Easy. |
Minimize braking and anticipate.  |
For urban driving this is the most important tip -- but takes the longest to learn and is the hardest to understand. It also requires the most concentration, so get out of the habit of using the cellphone or other distractions while driving or you will never get this one right. Braking wastes all the momentum that you've burned precious fuel to build up, so:
People invariably tell me, "Oh, I already do those things." O Rly? If you're not getting at least the EPA city rating in town, then no you aren't. Try harder and keep at it. |
Savings: Huge. Cost: Free. Difficulty: Moderate to advanced. |
Avoid idling. |
Idling wastes anywhere from 1/2 ounce to 2 ounces per minute, and those figures can double with the A/C on. Ounces quickly add up to gallons. Never let your car idle while parked, never idle your car to "warm it up," and kill the engine while stopped at longer lights. The idea that restarting an engine takes a lot of fuel is a myth left over from the days of carburetion. Restarting today's engines takes less fuel than idling for 10-15 seconds, and won't hurt your starter. When in doubt, kill it!
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Savings: Small to medium. Cost: Free. Difficulty: Easy to advanced. |
Techniques - Next Steps
The next set of tips offer require more advanced techniques, commitment or sacrifice, or offer more modest gains. Still very much worth considering for the serious hypermiler. Do what you're comfortable doing, and don't feel guilty about the rest.Pulse and Glide. |
Once you've mastered the above, this is the big one. It might seem counterintuitive at first, but engines are most efficient under a moderate load. Believe it or not, steady speeds present a very light load to today's overpowered engines -- even on the highway. If traffic permits you to vary your speed by 5 or 10 mph, you can save large amounts of fuel by alternately "pulsing" at a moderate rate and then coasting. If you do it right, you may find yourself spending more time coasting than pulsing! It can take a while to find the sweet spot -- usually 20-40% of the engine's power -- but on a smaller car this alone save you 10 mpg. | Savings: Medium to large. Cost: Free. Difficulty: Moderate to advanced. |
Limit A/C use. |
Sometimes you just need A/C, but it does increase your fuel consumption especially when idling. Get along without whenever you can stand to. Use a sunshade or park facing north on sunny days. When the A/C is on blast it, then kill it when you don't need it.
At highway speeds, though, use the A/C rather than driving with the windows down. |
Savings: Medium. Cost: Free. Difficulty: Easy to moderate. |
Start warm. |
Engines are very inefficient when cold. If you can park in a garage in winter, do. If you live in a colder climate and have a block or coolant heater, use it. But make sure to put the thing on a timer so it doesn't jack up your electric bill by running all night. | Savings: Small to medium. Cost: Varies. Difficulty: Easy to advanced. |
Park strategically. |
Minimize fuel wasted in parking lots. Whenever you can:
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Savings: Small. Cost: Varies. Difficulty: Easy to advanced. |
Equipment Choices
Monitor your fuel economy. |
To get the feedback you need to improve your mpg, you need a resettable trip mileage display. Most people get an immediate 10-20% jump in mileage simply because of the instantaneous feedback. Any car built since 1996 has a diagnostic port under the dash into which you can plug a device like the ScanGauge II. Get one. | Savings: Medium. Cost: $160. Difficulty: Easy. |
Buy Low Rolling Resistance tires. |
This could cost you nothing if you do it when you're buying new tires anyway. Consumer Reports tests tires for rolling resistance. Many Michelin models roll well and are clearly identified as such on their website, and the better Toyo touring radials offered at Northwest Les Schwab stores are also quite efficient.
Also, it is a popular but false myth that traction comes at the expense of rolling resistance. Michelin, Dunlop and Nokian all make excellent winter tires that grip fantastically well on snow and ice, yet boast low rolling resistance. |
Savings: Medium. Cost: from free to $500. Difficulty: Easy. |
Clear the roof. |
Even a bare rack without accessories costs 1-2 mpg on a midsize car. Add a couple of bikes or cargo box, and the damage jumps up to 4-5 mpg. Trunk/hatch or hitch mounted racks can carry bikes, skis and even cargo, and have a minimal impact on fuel economy. | Savings: Medium. Cost: Varies. Difficulty: Varies. |
Buy a more fuel efficient car. |
Hybrids and diesels are great -- as are less expensive economy cars -- but it's more cost effective to learn to adopt the above techniques and drive for fuel economy first. Then you'll get really good mileage when you later trade in for a more efficient car.
Some of my favorite fuel efficient vehicle choices are listed on my Cars web page. |
Savings: Potentially huge. Cost: Varies widely. Difficulty: Varies widely. |
Drive a stickshift. |
If you're already buying a car (see the previous tip), get a manual transmission unless you're buying a hybrid or your physical condition prevents it. If you can master the above techniques you can certainly learn to drive a stick. They are more efficient than automatics, and allow much more effective use of the techniques I've described above. Even though many manuals are geared lower than automatics, thanks to the additional control you get with a stick you're still likely to get better mileage. | Savings: Small to medium. Cost: Less than zero. Difficulty: Easy to moderate. |
How Not to Do it
NO truck drafting |
I do not draft trucks, and I do not recommend it. Never drive next to a truck or follow closer than 2 seconds. It's not worth the risk. Don't think a big SUV or pickup with "more metal around you" will make this safe, either. A loaded semi weighs 80,000 pounds and will squash your F-250 like a bug. Stay away.
I repeat: NO CLOSE-IN DRAFTING! Always leave a buffer of at least 2, and preferably 3, seconds in front of you. | ||||
NO extreme cornering |
While it's true that slowing down unnecessarily for curves and corners can waste fuel, it's not worth it to go racing around corners at the expense of safety.
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NO ignoring pedestrians
| Our roads can be a pretty unfriendly place if you aren't in a car. Let's all do our part to make it easier. It just might get us out of our cars more. That's good for both our economy and our health. Even a hypermiler can afford the tiny extra amount of fuel.
| Engine-off gliding?? |
The media go into a frenzy over this one and dismiss hypermiling by making this techique out to be both critically important and critically dangerous. It is neither. The savings are quite small, and you can get get mileage far in excess of the EPA ratings without doing it. That said, if you keep the key in the "RUN" position it's not as dangerous as it sounds: your steering wheel will not lock, your car will handle just like 1980s economy cars that didn't have power steering, and you have 4-5 pumps of the brake pedal (one pump is enough to stop from highway speeds) before you lose braking power. But if in doubt, do not do it!
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Aero modifications?? |
 Things like smoother hubcaps and smaller mirrors can easily save a couple percent, underbelly pans and wheel skirts may save yet more, and extreme measures like big air dams and boattails can yield huge fuel savings on the highway. But this is strictly DIY stuff that requires major effort and/or expense relative to the savings involved, and can have significant safety and legal consequences. If you're an accomplished and determined DIYer, by all means visit some online forums first (to find out what actually works), and then have at it. Otherwise, don't bother.
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My mpg
My Current mpg
Since early 2008 I've been driving a (gas-powered) VW Jetta Wagon originally rated at 24/31 mpg. I record my fuel usage at cleanmpg.com. Here's how I'm doing so far. After the first couple months of getting used to the car, I have not had a tank below 29 mpg except for a 26 mpg tank in December 2008 when we had 13" of snow and I spent a week driving on unplowed streets. Even with our now ethanol-laced fuel, I've had a number of tanks in the 34-35 mpg range and have been getting over 30 mpg even in town in the winter.
My Initial Results
Following are my Subaru's overall average from May 2007 through January 2008, and a graph of fuel economy versus daily high temperature over time. Note how mpg improves in the warmer months and goes down in the cooler months.
Prior to starting this exercise, I had consistently gotten mileage in the low 20s in the city and low to mid 20s on the highway on all 3 of my Subarus. In 2006 I made a conscious effort to drive less enthusiastically around town, but this only netted me a gain of 1-2 mpg. Even after the change I got about 21-22 in town in winter, 23-24 in town in summer, and 23-26 on the highway. The highway mpg was so poor due to high speeds (all too frequently in the mid 70s) and the presence of a roof rack frequently laden with a cargo box and/or bicycles.
Then in the spring of 2007 I started reading up on "hypermiling" and various techniques used to improve fuel economy. Up to that point I had assumed the 1-2mpg improvement from easing up on the gas was about all I could get. I never imagined I could see the 30% improvement I had achieved since I got serious about it that May. Even in winter I was able to average over 28 mpg, and in summer well over 30 mpg. On a long roadtrip I even achieved a achieved a 500 mile tank and 35 mpg.
Links
- cleanmpg.com, founded by Wayne Gerdes (the godfather of Hypermiling), is a wealth of information on driving for fuel economy. If you have additional questions about the techniques I've described, register for the forums on this website and ask away, and it's one of the nicest groups of people on any Internet forum.
- cars.html on this website describes the fuel efficient vehicles that I recommend.
- fueleconomy.gov is the source for specific fuel economy ratings of vehicles going back to 1985.
- edmunds.com is the best place for general reseach on cars going back to 1990, and has a Green Car Guide full of excellent articles related fo fuel economy.
- gassavers.org is another good source of fuel economy information.
- Numerous sites for specific fuel efficient cars, such as priuschat.com, tdiclub.com, fitfreak.net, metrompg.com, yarisworld.com and insightcentral.net have active discussion boards related to fuel economy. Go in with a thick skin though, because many of these forums have a lot of inexperienced, aggressive drivers who may be hostile to your ideas.
- The Tufts Climate Initiative issued ratings of carbon offset companies in 2007. Native Energy and Atmosfair are among the recommended choices.