Welcome to the 210 Club I must add also. I drive a 99 Black/Black with 160K miles. I bought it with 100K in 2003 for $19.5K. It was driven heavy on the highways. I don't think there is anything that is difficult to diagnose or fix on the 606s or W210s. You can get all the AC values and body codes from the climate control. A cheap OBD2 also gets almost all my codes. The only issue I thought I would have had to deal with is the head gasket. Long story short, it was an oil cooler. Oil cooler was taken apart, resealed and it has been good ever since. I will drive mine another 400K easy I believe before I have to rebuild it.