So when I got the car from the dealer it didn't run rough, or so I thought. I got 280 miles out of that full tank based on the range gauge. Then when I filled up I put 93 in plus some techron and by the end of the tank it ran smoother and I got 350 miles, now on my third tank the range gauge is saying 420 miles. So my question is, is it plausible that the dealership didn't use premium and/or the fuel system needed a scrubbing?
P.s. it's an 05 XT limited manual.