Hey, I was just wondering if any of you experience a drop in MPG in colder temperatures. I used to get avg 22-24 city, and 30mpg highway according to my trip computer during the summer. Now, I am only getting average 18-19 city, and 26 highway. I don't think it's anything mechanically related since I just had the 60k maintenance done. Of course I changed my tires from a 215-45-17 summer tire to a 235-45-17 all season tire. (maybe this?) What do you guys and gals think?


2003 stock quattro 1.8t.

 

There's allot of factors that contribute to your mileage.

From an air density point of view, cold air is denser meaning it contains more molecules per unit squared, therefore you get more air per intake stroke.... This is definitely a plus but here's the catch. Your car has to work harder to move all that cold air out of the way. just like any object that moves through the air. This aside from the usual factors i.e. tire pressure, engine tune, rolling resistance etc...

 

I have noticed the exact same thing, I've dropped 4mpg since the thempatures began staying below 40*F. I think I heard that the fuel companies mix the fuel differently because they need to ramp up production of heating fuel oil more during the winter. Maybe the winter mix isn't as efficient?

 

cold starts use lots of gas. seems reasonable that colder starts would use even more gas, as it takes the engine longer to reach operating temperature. just a guess though.

 

I know in Utah they switch to oxygenated fuels around late Oct, early November. This helps curb the inversion in the area during the winter months. I have noticed a decreasein fuel efficiency directly associated with this type of fuel.

 

winter gas sucks period but that's a little bitcrazy because i have a 2.8 and get around that much. maybe it's time for a tune up or stop punching the gas lol

 

I noticed this last year after I bought the car. I really don't think the winter fuel blend has all that much effect. Mine a 2.8L 12V usually does 24-25 Mpg tank to tank. In cold weather its down to 18-20 Mpg. I figure the engine has a cold start valve and probably a warm up valve just like theI-5s had so theres some difference right there.