My '09 non turbo automatic Forester was getting over 26 mpg average until 4 weeks ago. It dropped to around 21 and sometimes less. We had cold weather long before this occurred and my driving habits have not changed. I checked tire pressures, replaced air filter, bought gas at other stations and this week used cruise control on a 250 mile trip and still only get 21mpg. The dealer says winter fuel gets less milage and to pump the tires to 35 psi. Never had this problem with winter fuels before and 35 psi on a sub freezing day is a horrible ride. Any other ideas? I had installed a rooftop ski rack around the time this began but there is no way that could cause this much loss - especially at slower speeds. The car has 19,000 miles on it and had no problem last winter.