The next time you are following a car that starts off very slowly from a light or stop sign, or begins to slow down well before reaching an intersection, don’t get upset and start cursing at the driver. That person could be a hypermiler who is saving quite a bit of money by extending his gas mileage–and doing his or her part to help the country achieve energy independence.
The term hypermiling was coined by Wayne Gerdes, who is the leading guru of hypermilers. Hypermiling is the art of achieving gas mileage well beyond that of the EPA MPG rating for a vehicle. It is not unusual for a hypermiler to improve gas mileage by 35% or more beyond the EPA rating using simple techniques that require some skill and concentration to implement properly.
This doesn’t just mean driving slowly and avoiding fast acceleration. There are many methods that go beyond this. Here are just a few techniques that hypermilers use to improve gas mileage.
- Remove all items that create unnecessary wind drag on your vehicle. This includes luggage racks on cars and SUVs and tailgates on pickup trucks without toppers. It certainly helps if you have a aerodynamic car, but most vehicles are not very aerodynamically designed.
- Inflate your tires to the maximum recommended pressure. That number is found on the tire itself and goes beyond the auto manufacturer’s recommendation found on a vehicle’s door frame. This reduces the rolling resistance for the tires. The ride may be a bit harder, but the gas mileage should improve. You should only experiment with this if your car has fairly new tires. Some web sites suggest overinflating the tire pressure up to 25% beyond the maximum recommended pressure, but this sounds downright dangerous and probably is. Use common sense when applying any hypermiling techniques.
- Use the lowest weight oil recommended for your vehicle. Lower weight oil is easier to pump through an engine due to lower kinetic viscosity and is more efficient. Many hypermilers do not fill the oil all the way to the full mark on the dipstick, but rather fill it to the minimum mark or halfway between the minimum and full mark. This is said to improve mileage slightly by the reducing the strain on engine components.
- Make sure that you change your engine air filter at least once per year. Engines have to work harder with a dirty air filter.
- Go easy on the brakes and easy on the accelerator. Gerdes suggests an interesting technique where you drive as if you do not have brakes, which means accelerating very slowly from an intersection and allowing the vehicle to coast to a stop whenever possible. Acceleration and braking kill your gas mileage in city driving. You have to concentrate on anticipating your next action when using this method.
- Don’t drive beyond the speed limit. Faster speeds create more drag, which makes an engine work harder. You will have to experiment with this, because different vehicles have different optimal speeds where they run more efficiently. Slow speeds are not always better.
- Turn off the engine if you are sitting idle for more than ten seconds.
- Avoid using the air conditioner. This one is a bit controversial, because several studies show that the difference in mileage when using the air conditioner versus just rolling down the windows at highway speeds is negligible. It may, however, make a difference when driving on city streets or at slower speeds.
- Some hypermilers use the cruise control not just on the highway, but also for accelerating. Most cruise control devices accelerate more evenly than your foot and thus improve fuel efficiency. You have to be alert when doing this. Cruise controls do not apply brakes automatically. This could be a good technique for on-ramps when entering a highway.
- Many hybrids include mileage computers that calculate your fuel efficiency. If you want to add a mileage computer to your vehicle, the most popular model used by hypermilers appears to be the ScanGuage.
One of the favorite techniques used by hypermilers when on the highway is called drafting. Drafting is an effective technique used by truckers for years. It basically means riding behind large semi-trailers to take advance of the slipstream, which reduces aerodynamic drag. This method was studied by television’s Mythbusters team and was confirmed to improve gas mileage, although the best results are obtained when in very close proximity to a large truck, which makes some truckers nervous and could get you a ticket in some states. It is a dangerous technique.
If you want to learn more about hypermiling, there are lots of web sites that cover this topic. You can also visit Wayne Gerdes’ CleanMPG.com for a number of articles and tips regarding how to improve your gas mileage. Wayne set the world record for hypermiling when he achieved 180.1 MPG in a Honda Insight hybrid vehicle at a Hybridfest hypermiling event.