Used Mercedes seem to be a great deal because they are so much cheaper than the original price, but I've heard a lot of problems about the reliability of these cars, and of course that they are expensive to fix. How old/how many miles should the car have to even consider buying it? Is a 2003 that drives well and visibly seems great a bad buy if it has 100,000 miles? Or do these cars usually last 200k or more miles? Do they require more expensive oil and gasoline, or is it just preferred? Thanks for the help!