Rules of the road
You can achieve similar results by following these nine commandments of hypermiling. "It’s not brain science," Gerdes says.
- Brake sparingly. Coast up to red lights instead of braking (though you might want to watch your rearview mirror). Timed correctly, you’ll hit the green while still moving forward and expend less fuel accelerating again. A commuter should be able to pick up the timing sequence of lights along a route in three to four days, Gerdes asserts.
- To idle is to sin. Cars of recent vintage have fuel-injection systems that make starting an engine more efficient than idling. So if you’re going to be at a standstill for 10 seconds or more, cut off the engine. And if the drive-through line at McDonald’s is a long one, park and buy your food inside.
- Speed kills. "My Honda Accord, with good tire pressure and synthetic oil (see below), driven at 50 to 55 miles per hour, will get an average of 50 miles per gallon. It’s EPA rated at 24/34." So just follow the speed limit, or go at a slightly slower speed. To make himself and his slower speed conspicuous to faster drivers behind, Gerdes "ridge rides," meaning he keeps his right tires on the white line that defines the far right side of the slow lane.
- Avoid the big chill. Today’s cars can’t kick into their most efficient mode — called "closed-loop operation" — until the engine is sufficiently warm. There are ways to speed the process even if you don’t want to invest in an engine-block heater. If you’re on a round of errands, for example, always go the farthest destination first to bring up the engine temperature. If you make a series of short trips, the engine stays cold and never achieves maximum efficiency.
- Beware of drag. Car racks and other automotive appendages — even those flags honoring favorite sports teams — reduce mpg by creating drag. The problem gets worse with speed. "Think of trying to stand up in a 75 mph hurricane," Gerdes says. So if there’s something that can be taken off the car without compromising its operation or aesthetics, get rid of it. Driving with open windows is generally held to be better than using the air conditioning, but closed windows and no A/C are best.
- Lose the weight. For every 30 pounds of extra weight your vehicle carries, mpg decreases by anywhere from one-tenth to one-hundredth of a percent. That may not seem like much, but mile and mile it adds up. Jettison what’s not essential. If it’s summer and your trunk still contains a bag of sand to help you negotiate icy, winter roads, get rid of it.
- Pay attention to load. When you’re driving up a hill, keep a steady load on the engine. Gerdes recommends accelerating to a target speed and then locking your foot in position so the gas pedal is held steady. That will keep gas consumption at a constant level. Maintaining a constant speed, on the other hand, requires increasing the fuel burn rate as the hill is climbed. Do that and a vehicle that registers 40 mpg on a level road can see fuel efficiency decline to as low as 15 mpg, Gerdes says.
- Be not a hare. Jackrabbit starts might enable you to win the race to the next traffic light, but they’re murder on fuel economy. Gerdes explains that the best mpg is had at relatively low rpm levels. It may seem like you’re crawling if you try to accelerate at 1,900 rpm, he says, "but if there’s nobody behind you, what’s the point of going faster? You’re just throwing fuel away." And if you let the other guy beat you to the next light, his presence might just cause it to change to green, enabling you to keep going without braking.
- Set up for success. How a car is set up, particularly in the areas of tire pressure and engine lubrication, is critical. Gerdes recommends inflating tires to their maximum allowable pressure, a specification you’ll find printed on the outside of the tire. Higher pressure means less rolling resistance, allowing you to coast a greater distance. As for synthetic oil, it breaks down more slowly than regular oil and thus promotes efficient operation of the engine for a longer period.
Follow these basics and you’ll get your 25% increase in mpg. You can boost it even further if you’re willing to try a couple of more-involved tactics, such as avoiding left turns (and the braking that goes with them). Also, if you select parking spaces that allow you to leave by moving forward, you don’t waste fuel and motion backing up.