Summer has finally come to Lakeville. We do more driving in the summer months. Here are seven summer driving tips from Popular Mechanics (PM) that will save you gas dollars this summer.
Coast to a Stop
Brakes are necessary (duh!), but they’re inherently wasteful: They take the kinetic energy of a moving car—energy it took pricey gasoline to generate—and turn it into heat that’s lost to the air. Everyone knows that accelerating until the last moment then braking hard to stop is less efficient than slowly coasting to a red light. But PM’s test data (illustrated below) prove what a huge difference coasting makes. The lesson: Whenever possible, anticipate that a light will turn red and ease off the gas. Generally, the less you have to brake, the better your fuel economy.
Avoid Slowly Crawling Up to Speed
Conventional wisdom says that jackrabbit starts consume more fuel. But it turns out that nursing your speed up to the limit too slowly also lowers mpg. How can that be? Cars get poorer fuel economy in lower gears, and accelerating too slowly prevents upshifting at an efficient rate. The best acceleration rate varies with the vehicle, gear ratios and weight. But in our testing we found that taking 15 seconds to accelerate to 50 mph used less fuel than taking 30 seconds to reach the same speed, because the car entered its top, fuel-saving gear sooner.
Close Windows and Use a/c at High Speeds
It’s a fierce efficiency debate: Open the windows in summer to avoid running your energy-intensive air conditioner, or keep the windows closed and the a/c on to preserve your car’s aerodynamic profile. (We’ll leave aside the option of sweating it out.) PM’s testing settled the issue. Driving at 55 mph with the a/c running, we got 24 mpg; turning it off bumped us up to 28 mpg. Then we opened all four windows, one at a time, and lost 1 mpg per window until we were back at 24 mpg. So at that speed, it’s a wash. But aerodynamic drag rises exponentially with speed—the faster you go, the more the open windows hurt efficiency. The answer? Below 55 mph, open the windows and leave the a/c off. But at 60 mph or higher, keeping them closed and the air conditioning running will burn less fuel.
Monitor Tire Pressure
Keep your tires properly inflated, because low pressure increases rolling resistance. Few drivers check and adjust their tire pressure often, but it’s a good idea to do it once a week.
Plan Errands Carefully
Reduce the miles you drive by running all your errands in one trip. Making a run to the dry cleaner and then picking up the kids after soccer practice? Don’t make separate outings. A little bit of foresight will stretch your fuel economy.
Warm Up the Engine
Cars get better fuel economy when the engine is warm. So if you have a three-stop run, hit the farthest destination first, then work your way back home. A fully warmed-up engine will remain at an efficient temperature even if it’s parked for 30 minutes.
Make Right Turns Only
FedEx does it, and the MythBusters proved it works: When city driving, make as many right turns as possible, even if it means going a few hundred yards out of the way. Reducing loiter time—or idling while waiting for traffic to clear—saves gas.
Avoid Ethanol When Possible
Gasoline that has been cut with 10 or 15 percent ethanol, called E10 or E15, is an mpg killer. Why? Gasoline stores more energy than ethanol (119,000 Btu per gallon vs 80,000). So it takes more ethanol than gasoline to go the same distance.