Mark's Car-X is great. I visited for an oil change and a second opinion on some repairs (~$1,000) that my Volkswagen dealership suggested. Mark ticked through each repair (strut mounts, new tires, brake pad replacement) and explained why I didn't need to repair them immediately. I was shocked by candor. In general, I'd consider my self a pretty smart buyer, but I feel totally vulnerable when seeking out auto advice. I'd definitely visit Mark again.
Pros: Trustworthy, cost conscious, responsive service
Cons: Location is a bit out of the way