I would buy the Mercedes that still has the factory warranty not the starmark warranty (have heard they say everything is covered come time for repair) meaning the new design is a better choice. I have a 99 S420 and I had at least $8,000 done for me by through the factory warranty. I would only buy the 99 (not other years) S500 because that is the last year and they fixed the expensive AC evaporator problem. I have a 2001 S600 and it is a better choice for everyday driving but I always take the S420 on long trips. If you buy the S500, I would highly recommend you take it to a dealer for a complete estimate as one anomally could set you back alot. Repair of both of these chassis, requires a highly proficient technician because of the complex electrical and vaccum systems involved.