Wow! I always heard it was 1-3 MPG.
It also supposedly only matters to shut the windows for drag at about 70 MPH on aerodynamic cars.
That would exclude our loaves-of-bread-on-wheels I guess.

I like doggy AC better anyway unless it's really steamy.
I just leave my front ones open and back ones halfway.
I close the moonroof when I hit the highway but pop it up for ventilation.

 

Well when i did mine to compare the mileage difference i was only going 40 mph and i was in 5th gear.

 

Concur with the great mileage. Just got back last week from a 1800 mile trip out to Arizona, New Mexico, Nevada, etc. Many hours at 75 mph+ on I40. Avg speed for entire trip was 64 mph, and MPG was 29. Now back to daily commuting and 27.5 MPG at an average of 45-50 mph doorstep to doorstep.

 

I'll try it on my next tankful.
I'm at 504 miles right now and it's only been warning me for about 10.
It's time to put my spare 2 gallon gascan in it.

Gadzooks! I just realized another good excuse to have the filler tube on the passenger side.
So that I don't get splattered by passing traffic while I'm adding 2 gallons by the side of the road when I run out.

 

Can't you hurt some parts on newer engines if you run them empty? I know in the long run it's bad for your fuel pump because the fuel acts as a coolant, and keeps the pump cool, so it gets hot when there's no gas in the tank.

 

Good point.
I was kind of wondering about that.
I know there's at least 1.5 gallons in it so no worry yet.
I think I'll have to let it sit until I can fill it.

 

30MPG, 500 miles on a tank. It's what we all strive for and I believe is doable. BUT, you need to understand that you take the chance of causing damage to your car. CrazyCarKid is absoultly right, you can damage the fuel pump by running it empty. And to those who over fill the tank. WHY? do you know the cost of a new charcoal canister? Please explain the reason for over filling. If it just for bragging rights then you need to grow up, you will damage something some day. Don't take my word for it, find a trained tech that you trust and ask them. OH, buy the way, I'm 12 years a Chevy tech, 10 years a Chrysler tech, 2 years a Hyundai tech and 2 years in a Bosch shop. I've done my time and I would sooner maintain a car over fixing a car.

 

Oh, I know overfilling is terrible, but (knock on wood) I haven't had an issue yet in any of my cars. We get 50 cents off a gallon at Kroger, but you're limited to 4 fill ups per month, so I always try to get as much gas as I can to save.

 

I fill my GSX to the brim by holding the nozzle out as far as it can and sqeeeeezing every last drop it'll hold in.
I hold the rubber splash guard back so I can see what's happening.
It'll hold at least 1/2 gallon more that way.
The CC got chucked ages ago.

On the HHR I fill it until the pump won't add any more so it's close to the same level every time.
It will hold at least 1/2 gallon more but it'll never see it in the HHR.
I'm not about to buy a CC for it.
Don't know if it's covered under warranty and don't care.
It's not getting hurt.
I always fill at the same pump when I'm around here.
It's 12 miles away but I always take the long way home.

The fuel pump running dry is not a good thing so that won't be happening here either.
Don't know if that's covered under warranty either and don't care.

See my last post.

 

Yeah, I never over fill it if I'm just going to park the car... Usually I drive about 20 miles home from where I get gas, so I just burn up the extra that I put in anyways.