Spontaneous improvement in mileage

[roscoe]

I do a lot of highway driving and I consistently return a respectable 28 mpg. The last couple of tanks, however, mileage has improved noticeably. I now see 30 to 31 mpg highway (calculated the right way: miles driven divided by gas consumed).

Nothing's changed about my driving habits, cruising speed (75 mph), or the route I take to work. No mods either. Only thing that's different is I put on my snow tires about 2 weeks ago. But should hurt mileage, shouldn't it? Has this ever happened to anyone? PS: odometer shows ~15,000 miles. Thx

[gyrfalcon]

Narrower snow tires have less rolling resistance, and the colder temperatures mean denser air, better engine performance, and less AC compressor usage.

[1ToBeOn2Wheels]

Odd, I recently inflated my tires to their optimum pressure and my gas mileage has decreased ~1 mpg. I thought it was the other way around.

[ESC OFF]

Different tire diameter than your Summers?

[AudiS4]

Originally Posted by gyrfalcon

Narrower snow tires have less rolling resistance, and the colder temperatures mean denser air, better engine performance, and less AC compressor usage.

+1 on all the above, especially A/C usage

[Peoria1]

If the rolling radius on the snow tires isn't the same your odometer is no longer correctly calibrated. Smaller tires = more revolutions for the same difference, yields more miles on the odometer calibrated for the original tires.

[Xyloft]

Originally Posted by AudiS4

+1 on all the above, especially A/C usage

i lose 2 mpg on my winters typically because my rims are heavier than the stock sport package 17s. I also put 225's all around instead of 205s up front.


did you change yoru rims? go from 18 to 17? any weight shaved off the driveline is going to give you more power/better mpg (given a light foot).