I have had a 2003 ML320 a 11 ML350 and now have a GLK 350. I had the first ML for 10 years and put 110K miles on it. It was almost completely trouble free needing a water pump and crank position sensor at 110K and the low range motor needed to be cleaned and greased (mostly due to non use) at 140K. It was sold to a friend and still is running with only routine maintenance, now at 220K. The 2011 ML was a more refined vehicle, quieter and more comfortable but thirsty (16-20mpg) they both were used for towing and neither seemed to be taxed with the extra load. Gas mileage dropped to 9-11 for both towing up to 7000 pounds with the 11. We sold the ML350 to a family member and it is still running strong with no significant problems. We got the GLK because we wanted a smaller vehicle. It is by far the most fun to drive for an SUV it has 300 hp
and takes off like a rocket. Handling is a little like our 2000 C230 sport with a bit of a top heavy feeling. The rear seat room and cargo capacity in the GLK is lacking but it is only the two of us now so that is fine. Mileage is in the 24-30 range.

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Dave
88 300E 250K Sold
2000 C230K Totaled @104K
2003 ML320 156K Sold
2009 E350 4Matic Sport 46K Sold
2011 ML350 60K Sold
2014 GLK350 46k
2012 GL450 55K