Ok, as promised in an earlier thread, here's the final results of my 'research' regarding gas consumption while driving with top up and top down.
In order to keep things as consistent as possible I use the same gas station [QuikTrip, 93 octane] for both tanks of the test. I also ensured the tire pressure was the same for both tanks [30 front / 33 rear]. I didn't run the tank all the way empty on either test, but I tried to refill as close as possible, so for the top up test I drove 301 miles and for the top down I drove 259 miles. I don't have any modifications to the engine/air intake/etc. It's all stock.
On both tanks, I drove maximum of 70 mph, using cruise control as much as possible to maintain the same speed.
With the top closed up I used 11.371 gallons for 301.0 miles. That equates to 26.471 miles per gallon.
With the top down I used 9.677 gallons for 259.0 miles, which equates to 26.764 miles per gallon. Slightly better!
The week I drove with the top down was slightly cooler than the week with the top up, so I don't know how much that affects gas mileage, but all in all it appears as though I get almost exactly the same gas mileage regardless of whether the top is up or down.
In order to keep things as consistent as possible I use the same gas station [QuikTrip, 93 octane] for both tanks of the test. I also ensured the tire pressure was the same for both tanks [30 front / 33 rear]. I didn't run the tank all the way empty on either test, but I tried to refill as close as possible, so for the top up test I drove 301 miles and for the top down I drove 259 miles. I don't have any modifications to the engine/air intake/etc. It's all stock.
On both tanks, I drove maximum of 70 mph, using cruise control as much as possible to maintain the same speed.
With the top closed up I used 11.371 gallons for 301.0 miles. That equates to 26.471 miles per gallon.
With the top down I used 9.677 gallons for 259.0 miles, which equates to 26.764 miles per gallon. Slightly better!
The week I drove with the top down was slightly cooler than the week with the top up, so I don't know how much that affects gas mileage, but all in all it appears as though I get almost exactly the same gas mileage regardless of whether the top is up or down.