Both are likely to be completely reliable, as well as having all the on- and off-road capabilities you want. They have a range of sizes and prices, and good service departments too (if you every need a repair).
As long as you can get the VW at $500 over invoice and don't keep it beyond the factory warranty you'll love it if it can stay out of the service drive. I'm a VW person (had a Jetta before my ML320) but know the truth - VW service is poor. VW typically doesn't have loaner except on extended services and then don't keep loaners on site. Expect to wait 20 min to get the van to a rental center where after another 30 min they will give you a very tired Corolla. Also, don't even think about third party warranties.
MB service is not much better but as long as I get a loaner I don't suffer. Even the smallest problem would take overnight. I used to schedule my MB service appointments on Friday so I could use the loaner all weekend which just happened to coincide with long out of town trips! Must of saved my ML 000's of miles[:D]. With all the rebates and mounting inventories you should be able to get the ML far below list. Buy the longest factory extended warranty you think you might need and remember that the warranty is subject to discount and many dealerships will sell them at a big discount - I live in Houston and bought my extended warranty from a SF dealer.
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warning triangle, 133,000 miles
To me the above prices don't look right. In order to compare these two SUVs one needs the correct prices and then we can talk about quality, ride, service, depreciation, etc.
Cy
The sticker on the ML350 is acually 45k, I've never typed that big number before, not used to it[;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)][;)]
OK, now that we have the exact numbers, for 37k I would go for ML 350.
The car is mature, has none of the old problems, is built like a rock, and is a Mercedes Benz.