I'm looking at a pre-owned (certified) MDX with 49,000 miles on it but I'm a little worried about buying a car with so many miles on it! It's a 2004 so the powertrain warranty will last until 2011. How do I know if the previous owner(s) took good care of the car? And how many miles can you typically get out of a MDX? Is the powertrain warranty a good warranty?