MPG Anomaly!

total loss from winter fuel varies greatly from area to area. there is like 12 blends of summer fuel nationwide but about 40 blends of winter fuel.

cold air is denser which increases air friction drag.
colder engines dont run as efficiently
winter fuel has less calories which can result in a 1-10% reduction in energy per unit. basically, the colder the area you are in, the greater the reduction in energy per gallon.

also, think about it. even in the summer time. whats the difference in mileage in the first 3 minutes verses minutes 13-15??

usually quite a bit. that is why short trips make a big hit on the mileage. less time to make up for that 20 mph bar on startup.

granted the 2010 is supposed to heat up quicker so it gets into the good or "normal" mpg's quicker. have not had a real cold snap yet to test and short trip calcs are fine, but in the long run, its the tank numbers is where the differences are seen.

i have a thread going where i am tracking my short commutes to work under varying conditions. have 3 legs to go, one will not be until next summer (started project late...) but current one is with winter formula gas, the next one will be with lights in both directions which will start next week on DST...

now right now, we are in "monsoon" weather. which means warm, rainy (overnight "low" last night was like 55º...high today, around 60) so mileage aint all that bad.