I bought a new 2006 Subaru Forester. It's been a great car and was getting great mileage: 23 city, 27-28 highway, 24-25 mixed.
At 3,500 miles I took it to the dealer for an oil change. Since then, my mileage has has dropped to about 18-19 city, 22-23 highway, and 20 mixed. Any thoughts on what might have caused such a severe drop?
My driving conditions haven't changed, and I've tried switching gas, without any change.