Monday, August 18, 2008

How to Hypermile

How to Hypermile

from wikiHow - The How to Manual That You Can Edit

Hypermiling refers to a collection of driving techniques aimed at improving your car's fuel efficiency by reducing the demands placed on the engine. Since it's possible to improve fuel economy by 37% just by changing the way you drive[1] hypermiling is gaining interest in light of high fuel costs. While some hypermiling methods are controversial and potentially dangerous, this article will focus on safer techniques that can still save you gas and money.


  1. Drive as if you don't have brakes. If your brakes were in bad shape, you'd increase the amount of space between your car and other vehicles on the road so that you have ample room to slow down naturally, without depending completely on your brakes. Even if your brakes are perfectly fine, driving in this manner improves fuel economy because you maintain slower speed, reduce acceleration, and place fewer demands on the engine by going easy on the brakes.This may be frustrating and difficult, however, if other drivers keep cutting in front of you. You should keep your foot ready to use the brake so that if you do need to stop suddenly you can react quickly. Also, you should never roll through stop signs; the increased risk of a car accident and/or traffic ticket is not worth a few extra cents saved in fuel costs.
  2. Be gentle with the accelerator. When you slam down on the gas pedal, it pushes more fuel into the engine, making it run faster (and lowering the fuel economy and increasing your output of pollutants). Push the pedal down slowly, and lift it up as soon as you know you're going to need to stop (when you see a red light, a stop sign, or brake lights from the car ahead of you) so that you can coast the rest of the way. You should never need to push down the pedal by more than an inch (2.5cm).[2] Some cars are even being designed with pedals that "push back" when you're accelerating too aggressively![3]If you have a choice between various routes, go for the one with the least number of stops; country roads are good because you don't have to stop (and go) as much and you don't have to accelerate/brake to get on/off (like with the highway). If you're driving on sloped roads, it's useful to think about where you should come to a full stop because that'll affect how hard you need to accelerate:
    • Avoiding stopping on an incline heading upwards. Starting from a dead stop on a hill is the worst scenario in terms of fuel economy. Stop at the top of the hill, or stop before you climb the hill (if it's safe).
    • When coming down a hill and faced with a red light at the bottom (where it levels out), try to stop well before the light so that you can use the remaining downhill slope to your advantage when you need to move again.

  3. Avoid idling. Turning off the engine when you stop for more than one minute can improve fuel efficiency by 19%.[4] In cold weather, letting your car idle to warm up reduces fuel economy and creates additional pollution; all you need to do is drive gently for 5-10 minutes[5] and if you're following the previous two steps, you're going to be driving gently all the way anyway.
    • If you have multiple stops in one trip, plan it so that you go to your furthest destination first and make the rest of your stops on your way back. By taking your longest drive at the beginning, you give the car enough time to warm up for the remainder of the trip; if you took the short trips first, your car would take longer to warm up (because of the brevity of each trip). Since engines do not operate efficiently until they are warm, taking your longest drive first increases fuel efficiency.

  4. Minimize the engine load. Generally, it's better for your fuel economy if you maintain a steady speed, which is why using cruise control and driving at or below the speed limit is an important part of hypermiling. If you're driving on a hill or any kind of varied terrain, however, you need to consider how much work the engine is doing. Sometimes, a steady speed means unsteady strain on your engine, which lowers fuel economy. Let's say you're approaching a hill. Do not slow down, or else your engine will have to do extra work to maintain your speed. In fact you should, within the limits of safety, gradually speed up as you approach the hill, so that momentum will help you up the hill.
  5. Park for easy departure. Instead of searching for the perfect spot close to an entrance (which will involve stop and go driving, especially with pedestrians involved and other drivers pulling in or out of their spots) pull into a spot that's further away from the entrance. Look for the parking spot with the highest elevation and park face-out so that when you start the car and the engine is cold (at the lowest efficiency) you can use gravity in your favor without having to spin your car around. Some hypermilers recommend coasting out of the spot in neutral, but this is not a good idea because if a shopping cart or a small child happens to get in your way, the inability to use power steering and brakes (and the possibility of the steering wheel locking) can increase the likelihood of a collision.
  6. Check tire pressure regularly. If the tires are incorrectly inflated, then there will be excess drag, and not enough surface contact with the road. The car therefore suffers a drop in efficiency.
  7. Reduce the junk in the trunk. The more weight you're carrying, the more the engine and drive-train have to work. Removing all of that unused junk in the trunk increases efficiency.


  • These driving techniques won't work if you don't properly maintain your car, which is recommended for fuel economy whether you're hypermiling or not:
    • Use of high performance Iridium tipped spark plugs lead to a larger combustion spark which gives you a fuller cleaner burn in the combustion chamber, giving you a smidge more power, better fuel efficiency and lower emissions.
    • Align and balance the wheels.
    • Use the lowest viscosity oil that is recommended by the manufacturer. Using anything lower than what is recommended can be unsafe. If the car is not "taking oil" - burning it or leaking - switch to synthetic oil (and ATF), as those greatly reduce internal powertrain friction, improve mpg and longevity. At the same time, oil changes can be done much less frequently, thus compensating for higher oil cost. Read your car manual - there are virtually no modern vehicles left that will recommend 3000 miles oil changes anyway.

  • Keep an MPG journal to track your improvements in fuel economy. One could purchase a "driving habit modifier" - a device that plugs into the onboard diagnostic system and shows actual mileage, on cars not equipped with trip computer and made after 1996. Staying "on top" of ones mpg visually, radically changes those habits.
  • Pay attention to the weather. If at all possible, avoid driving on windy days, especially if you're taking a long drive on the highway.[6] If the weather's rainy or snowy, you won't be able to hypermile as efficiently (and you shouldn't--safety first).
  • The debate between using air conditioning and opening the windows is moot (an easy rule of thumb is when traveling under 45 MPH open your windows and over 45 turn on the AC)--not only is the difference negligible[7] but hardcore hypermilers don't do either. They bring ice water in the car with them so they can stay cool with the windows cracked and the AC off.


  • Avoid putting yourself or others in danger.
  • Driving in this manner could evoke road rage from other drivers.
  • Stay away from extreme hypermiling techniques. They are too risky, not only for yourself but for the safety of other drivers.
    • Don't roll through stop signs or cut corners at high speeds to avoid braking.
    • Don't turn off a car's engine to coast down hills. Turning off your engine will cause you to lose your power steering and brakes.
    • Don't over-inflate tires to decrease rolling resistance because you can lose traction and get into an accident hurting you or others.
    • Don't tailgate a big rig in hopes of cutting wind resistance. The 1 second rule puts you more than 75 feet from the rear of the trailer. The distance needed to get in the low pressure zone behind is less than a dozen feet.
    • Be aware that tailgating a big rig (semi or truck) can kill you. If the truck has a tire blowout while you're tailgating, it can throw the tire tread through your windshield, total your car, and severly injure or kill you. Trucks are extremely heavy, with corresponding handling challenges so the safest place is to not be in the same proximity. A simple web search can provide examples.
    • Driving under the speed limit in heavy traffic (where other vehicles can't pass you safely) is VERY dangerous and causes more accidents than speeding.

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