Hello HiHo, the best year for an ML would be the '05 ML350. Last year of that body style which typically means all the kinks are worked out and it has all of the latest technological equipment available at that time. Also they produced a Special Edition model because they were doing away with the body style the following year. It gives you cosmetic features not found on any ML (hood, bumpers, grill, running boards, wheels) and some optional equipment became standard plus the wood is different.

If you are set on an ML320 (original engine) then I would do the '02/'03 model year.

You may want to consider the '01 ML430 (last year for that engine) which gave you bigger wheels and more standard equipment. The gas mileage difference was about 2 mpg according to the window sticker back then.

Hope this helps.