My old man used to tell me you'd get better gas mileage in a car with the windows rolled up, since it had less wind drag. I never tested it, but it seemed reasonable, and I did not really feel the urge to argue the point with him .

My question now is would you get better mileage with the top up, or would it have any real impact? The wind seems to kick over the cabin pretty well, and I hadn't thought about it (or the old man's point) until now.

I have a descent mileage road trip in the future and wondering about it. Since it is heading across the Fl panhandle, it should be warm enough to run topless !

Yea, I'm bored and the mind wonders at times.....

Allen

 

I doubt the impact would be that great but I think mileage would be better with the top up.Now the question is with the top up would you have the a/c on?If so how does that mileage relate to the top down. IMO put the top down and your foot to the floor!

 

Agreed !

Didn't think about the AC part of it, but figured it would be off- never figured AC would impact an LS1 much to start with.

Allen

 

This has been tested. And it's better to have the A/C off and the windows down if your driving slowly. If your on the interstate then have your windows up and turn on the a/c. Obviously if your only concerned about mileage leave the A/C off and roll the windows up.
Convertables have terrible aero drag with the top down. So up, even with the A/C on is better.

 

yeah i am a victim of this "drag" with the top down.... i raced a trans am ls1 with my top down from 55-130ish and it couldnt keep up i was like 3-4 car lengths behind

 

Yup. The breaking point is around 40mph. Slower than that -- open the windows. Faster, close them and turn on the A/C.

The breaking point is probably lower for efficiency with the top down -- I'd guess 30-35mph.

That said, who cares? If the sun is out and it's warm enough, put the top down, feel the air around you, and get on the road!

 

No doubt when the top goes down the mileage and the performance goes down too.

 

My over-riding view point.... Just curious!

Got to Pensacola with the top up- was a bit chilly on I-10. Got even colder with the pause to talk to one of FHP's finest !

Have to put a couple of things on hold now after 87/70 and soon to be $180 lighter...... crap!

Allen

 

Ouch, nothing like a ticket to ruin a nice ride. Good luck.

 

With the top down I got 30 mpg on the road, about 23 mpg around town. Now with it most of the time up it adverages 21 mpg around town.

 

mythbusters has tested the old tailgate up or down gas mileage myth and proved by simple physics (i believe they call that an oxymoron?) that it's better with the tailgate up because it creates a pocket of swirling air that sends the airflow straight over the bed never hitting the tailgate...using the same basic principle, it seems like there wouldn't be much of a difference with the top up or down. now the a/c is a different story...it puts more drag on the motor which i know reduces power because you can feel it bogg when you turn it on

 

I can notice a power difference, especially in higher speeds with the top up or down. The speedo just doesn't climb as fast with the top down...especially past 90 or so.

 

yeah i think mythbusters are retarded... i just raced a T/A last night and we never pulled on one another... a few months ago i raced a bone stock WS6 and he pulled 3-4 car lengths. i could tell my car was just not giving me what it normally would considering the air was hitting my back seats at 100+

 

Mythbusters never tested a convertable, they tested a truck with the bed up and bed down.

 

I think he's right.

I have my windows down 90% of the time (weather-permitting).

I took a 2.5 hr. long trip a month ago and it was too cold to have the windows down, yet still warm enough inside the car for no heat. I think I must have got 1-2 MPG better on this highway trip with the windows up, no A/C or heat on and the cold air outside.