Is it the gas?

[gurps]

I've never tracked mpgs like this before, so help decided if this is expected normal behavior for this time of year or something else. Starting with my Aug 26 fill up my millage has gone down around 10% for the last 5 tanks. Is it winter gas? I installed new brake rotors and EBC red pads and changed the transition fluid with Royal Purple Maxi Gear 75w-90 just after that last good fill up. could a brake be dragging, or the trany fluid too thick?. Is my BP airfilter clogged? ( had it since mile 2420 )
I had been trending up since I purchased the car, with Aug 26 being the peak at 41.7mpg ( 6954 miles ), my average for the life of the car is 36 mpg. The last 5 tanks have been 38.9, 37.4,36.7,38.2, and 37.4. My driving habits are not perfectly consistent, but overall, not much has changed since I got my smart.
Here is PA we get up to 10% ethanol year round for pollution control but I think the winter/summer blends are about changing something else about the gas.

Thanks
Tom

[rfernatt]

Sounds like it could be the transition to winter blend fuel. It's usually about a 10% hit on economy.

[chieftmc]

Sounds like winter blend to me