Could it possibly explain a 10-15% drop in my MPG this winter?

I bought my '06 MCS at the end of last March. After break-in, my mileage seemed very consistent - 23 around town (30mph avg) and say around 28 highway. This winter, however, my around town mileage dropped to around 20, and on the highway, I can't seem to break 23. IMHO, same type and style of driving.

Now I have swapped from my summer wheels from superlight SSRs/GSD3s to S-lites/Pirelli Snowsports (about 13lbs per corner diff), but I can't imagine that would make much difference, esp. for constant velocity highway miles.

I'm at about 10k miles, and I rely on the OBC, although I do calc its accuracy nearly every tank (it's always within 1mpg accurate). Car/engine seems to be running great.

Can't think of anything else that would cause that much of a change, except that cold air is denser and the Mini is an aerodynamic brick .

 

I doubt it is the air. Could be the tires. That's more than 50 lbs extra. And how's the tire pressure?

 

Also winter gas blends hurt mileage. Don't be scared because your mileage dropped during the winter months, it will come back when summer blends of gas come back.

 

Colder, denser air in the intake also means more fuel added to maintain the proper mixture. Great for performance, not so great for economy.

 

You may also be letting the car warm up a bit longer at start-up. Also wheel spin on ice and snow will have an effect.

Mark

 

Check tire pressure, if low, that can get you a 5-10% loss. Tire type helps too - some tires don't roll as well as others, and snow tires have that nice soft squirmy tread necessary to hold on snow and ice, but they don't roll as well. That nice, cold dense air that the supercharger loves is also harder for the Mini Aerodynamic Brick to push out of the way, so that's a factor. Winter fuel blends tend to have more ethanol, which hurts mileage. Even non-ethanol blends are not as good (or so I hear). Low traction surfaces, more time idling, running more accessories (higher speed fan, defrosters) - all have an effect.

 

If you're a pilot, however, you gotta love cold air. Much better lift.