DIY ZERO: Better Mileage

Susan Nolan

Sure would be nice to have an electric car these days! In the meantime, driving with care and doing routine maintenance can boost your mileage and reduce the carbon footprint of your gas burner.

The easiest, most effective way to get more out of a gallon of gas is to slow down. Most cars run at their maximum efficiency around 55 mph. Hard to believe it makes that much difference, but just holding your hand out the window will show that overcoming air drag is a significant part of the work your car does. Fuel efficiency falls almost 30 percent between 55 mph and 80 mph.

Another easy change is to drive more smoothly, accelerating and braking gradually. Sudden stops and jackrabbit starts waste fuel. Coast up to a stop sign (where traffic allows). Increasing your following distance will accommodate changes in traffic speed with less need for braking.

Turning the engine off for stops longer than 30 seconds is suggested. Idling consumes a quarter to half gallon of gas per hour. Warming up a cold engine is a good habit, allowing oil to splash around and lubricate but, again, ten to 30 seconds is plenty of time. If you’re trying to warm the inside on a cold morning, getting in and driving is the fastest way. Cruise control increases efficiency, except on hills. Combining trips, and planning an efficient route, perhaps with a list of stops in order, will save time as well as gas.

Okay, so those are some changes for the driver. For suggestions related to the vehicle itself, good maintenance can increase mileage and extend the life of crucial components.Your car wastes energy (gas!) rolling around on mushy underinflated tires. Gas stations in California are required to provide free air to customers. The amount needed is embossed on the side of the tire. The station’s air nozzle has a pressure meter so you’ll know when you’ve added enough. You can test at home with an inexpensive gauge (under $10) that fits in your glovebox. Proper inflation will extend the life of those spendy tires as well. Oversized tires increase road friction and reduce gas mileage. A tune-up, with fresh spark plugs and a new air filter, will also increase efficiency.

Oil’s job is to reduce friction in the engine. Clean oil helps it run cool and increases engine life. Dirty oil will wear down the engine so it runs less efficiently and emits more pollution. On most cars this job isn’t very hard to do yourself with simple tools. Your gearhead friend can get you started, or there’s a good introduction here: 

Get the lead out. Take out heavy stuff you’re not actually using—when was the last time you needed a tow chain or really used that sports gear? If that rooftop cargo carrier isn’t carrying anything, better to leave it in the garage til you really need it. Besides the weight, it creates significant air drag. A rear-mounted carrier of equal weight will have much less effect on performance. Even empty roof racks contribute to air drag efficiency loss.

Air conditioning is a big energy hog, since the engine powers the compressor. Unfortunately rolling down the windows or opening the sunroof creates air drag, especially at higher speeds.

Electric cars and hybrids can take advantage of regenerative braking, where the energy lost in slowing gets recaptured. When the driver takes their foot off the accelerator and steps on the brakes, or just allows the car to decelerate, the electric motor actually reverses direction and feeds power back to the battery. This can be maximized by minimizing use of the brakes (when it’s safe).

For a major geek-out on these issues, with references, this article is excellent: And hey—don’t forget the bus. It only costs $2.10 to go anywhere between Trinidad and Scotia.