Be very careful with 2001 and below ML's there are quite a few issues (like early 2004 Touaregs) that need to be and are still being worked out. I previously had a 1999 ML430 that was a bucket. Maintenance wise it would be cheaper then the treg but intervals would be roughly the same. Power would be substantially less then the treg as well as the road presence. Personally, I would never purchase another ML, or Treg for that matter. That is just my personal preference, but if I had to choose I would choose the Treg. The only thing I would say the ML has going for it is ride comfort, my old ML was very solid, no rattles and random crap moving/making noise inside. This however is compared to a steel suspension treg, not air.