Which has a better fuel consumption ?

Question

A car driven with it's windows wind down which will have air resistence or a car driven with it's windows closed which will be more aerodynamic but it's air-conditioners on, thus consuming more energy ?

Answer 1

A 91 Explorer does better with the windows up and air; I got 23 M.P.G..

Answer 2

Depends on the speed.

If you're going freeway speeds, driving with the windows up and the AC on will give you better gas mileage.

If you're driving at slower speeds, driving with the windows down and the AC off will give you better gas mileage.

But this will only make a 1-2 mpg difference.

Answer 3

Roll up windows or use A/C

When driving on the highway, most of a vehicle's power is used simply to overcome aerodynamic drag. On the other hand, air conditioning also uses a lot of power.

Drivers are often told that keeping the windows rolled up, which significantly reduces drag, and using air conditioning actually results in better fuel economy than driving at high speeds with the windows open. In fact, CNN/Money has offered the same advice in a story we've run on our site.

In Edmunds.com's test, conducted at a steady 65 miles per hour, "windows down" or "A/C on" made virtually no difference in mileage.

The Mustang got 4.1 percent better mileage -- 30.7 mpg vs. 29.5 mpg -- with the windows down. The Land Rover got 1.6 percent better mileage with the windows down, a difference of just 0.3 miles per gallon.

Basically, the extra fuel used by the air conditioner is made up for in improved aerodynamics at high speeds. Your not really saving any fuel but, at least on the highway, the A/C isn't costing you appreciably either.

Verdict: No difference

Avoid hard acceleration

You've probably been told before that rushing up to stop lights and racing away from them wastes gas. Turns out it wastes a whole lot of gas, according to Edmunds.com's test.

Slowing zero-to-sixty times to 20 seconds instead of 10 to 15 seconds makes a big difference in mileage over the long term. Braking slowly and gently helps, too.

Driving the Land Rover gently resulted in a 35.4 percent increase in gas mileage while feather-footing the Mustang garnered a 27.1 percent mileage increase.

Verdict: Big difference

Properly inflate tires

Not having enough air in the tires can cause a number of problems, including a potentially dangerous blow-out. But it also reduces gas mileage.

In Edmunds.com's test, the mileage improvement with properly inflated tires, compared to slightly under-inflated ones, was slight but noticeable in the Land Rover but non-existent in the Mustang. Still, for safety's sake, keep enough air in your tires.