[Blood of Tyrants]

First of all, they are good ideas but there is NO WAY to increase your efficiency by 50%. Maybe 20-25%, but not 50%.

Second, rolling the windows down will only help during stop and start driving. For highway speeds, turning the AC off and rolling the windows down actually creates more drag and uses more fuel than the windows up and the AC running. For those of us in the muggy southeast, running the car with the AC off simply isn’t an option.

[antiRepublicrat]

For highway speeds, turning the AC off and rolling the windows down actually creates more drag and uses more fuel than the windows up and the AC running.

That depends on the car, its aerodynamics, drivetrain, etc., the speed you choose to drive and other factors.

[Ticonderoga34]

Second, rolling the windows down will only help during stop and start driving. For highway speeds, turning the AC off and rolling the windows down actually creates more drag and uses more fuel than the windows up and the AC running. For those of us in the muggy southeast, running the car with the AC off simply isn’t an option.

I use the AC with the windows up on the freeway and turned the AC off and roll down the windows in city traffic and have noticed a increase in gas mileage using that strategy. But like you said, sometimes it is just too hot not to use the AC all of the time.

[pas]

Not true. Myth Busters did this one and the windows down was actually more fuel efficient.

[Oshkalaboomboom]

Second, rolling the windows down will only help during stop and start driving. For highway speeds, turning the AC off and rolling the windows down actually creates more drag and uses more fuel than the windows up and the AC running. For those of us in the muggy southeast, running the car with the AC off simply isn’t an option.

I posted about this before in a different thread on hypermiling. They did a whole bunch of mileage studies using a Toyota Camry as their test vehicle and they found that:

1. Using the air conditioning shaved off less than 1 MPG, and

2. Opening the windows had no measurable effect on mileage at all.

I also live in the muggy Southeast and I would only run with the windows open if I was down to fumes.

What was the biggest improvement on mpg? Slowing down.

[Minutemen]

It wasn’t an option at all, before all cars had air conditioning.

[maine-iac7]

For highway speeds, turning the AC off and rolling the windows down actually creates more drag and uses more fuel than the windows up and the AC running.

LOL

Reminds me of a trip I took years ago with a friend in Calif.

We were returning from a weekend trip for a wedding in Eureka, to get back to Santa Barbara County where he was a Sargent with the Santa Barbara Sheriff's dept.

He had a deadline to meet in getting back on duty and needed sleep so he turned the wheel over to me...Wheee...

The car was a sweet, silver, 1963 Corvette Stingray, split window, fuel injection 327...no air cond.

It was a hot Calif. day - but he said to keep windows up to make better time by cutting down on drag.

It was fine by me - he NEVER let anyone drive his "Silver Bullet" - it was a sweet little car.

Here in Maine, there's not a whole lot of days one "needs" air cond., and on those days, I carry a bottle of water with a fine mist spray - it works amazingly well for cooling -