Mark Miller Subaru

I took my Subaru Legacy Outback to Mark Miller to resolve a power problem and was quoted an amount that seemed high, so I went to a competing dealer down the street who identified the same problem, but quoted me less than half the amount Mark Miller quoted for the same repair. I don't see a reason why it would cost more than twice to repair the same problem at Mark Miller, especially when the other dealer's facility was newer, cleaner and more professional.