I recently bought a 2000 Outback with a 5 speed, and the car has been running well and everything appears fine. I drive across the state for school and thought I'd calculate the gas mileage I was getting. After driving 187 miles on the highway I had to put almost 11 gallons of gas into it. that's just over 17 Miles per gallon! Has anyone else had this problem or know a possible cause for the mileage being this bad?