Gas Mileage after tune / snow tires?

[66goat]

I know you shouldn’t change to many things at once but this is the way it goes. I got the VMS tune two weeks ago at the same time I put snow tires on the car (Bridgestone Blizzak 19”). My gas mileage went from 22.5 mpg. to 19.5 mpg. the tire pressure went from 39psi to 32psi. The car runs great after the tune and I know you guys will say get your foot out of the throttle, but I average 900 miles a week mostly highway.

[bobyoung]

I also got the VMS tune but it's tuned for the HRSK and CAI which I haven't had time to install yet. At first I didn't like the way it ran and my gas mileage seemed better, now it's running REALLY good and it seems to me I may have lost a little but it is so hard to really get it accurate. I was averaging between 18 and 19 mpg before now I'm somewhere around 16 but it's too soon to really tell and I have to get the other two parts of the equation in there, hopefully tomorrow. I think I am playing with it a little more too, these cars cab be so good on gas when you just put along. ..but who wants to just put along?

[-Ray-]

Winter gas kills mileage. Wait until Spring to start testing it.

[Chewy]

Winter gas kills mileage. Wait until Spring to start testing it.

Agreed! I never really noticed a huge change from summers to winters. I am getting a new(for me) ECM from VMS here shortly.

Mine runs WAY rich right now.

[66goat]

Thanks guys… I was thinking that the winter gas may have something to do with it.

[bobyoung]

I'm going to check mine out this week, I finally was able to get the Roto-Fab in and it runs a hundred times better.
Going from 39 to 32 lbs in your tires will give lower mileage too.

[09PBMGT]

Snow...? We don't get that here. What does it look like? I've seen it on T.V. J/K That's why I moved from the Midwest fellas. I don't miss scrapin' off that ice at 6 a.m.

You chaps enjoy the snow, while I'm playing golf!

[appletonrc]

There are many reasons for MPG drop in the winter. As others said, tire pressure is one. Another is just the fact that it takes longer for the engine to get "warm". The car runs in a rich mixture until it is at operating temps. This obviously takes more gas. On mornings like today (-7), I'll let it idle for 5 minutes before driving. That doesn't help. Air density is another, cold air is dense, so it takes more gas to keep the ratio the same (means more power too)

I just came from another G8 board and have posted this pic there.. I'll repost so you can see what snow is

[-Ray-]

Welcome to the forum!

[MANOFSTEEL69]

Welcome!