Phideaux here, (Australian)
Lots of people 'like' the Nissan Murano (I was never one of them). First test of first iteration here in Oz found that the thing just shut down if the gearbox overheated. Ran okay a day later... If you live in Arizona or some such, might wish to think on this. They do have a nice V6, tolerable power-to-economy. If you do rough-road/off-road, the Murano is at the soft end of soft-roader.
The big advantage of the Subaru (any Subaru) is symmetrical AWD. This means if you're in snow or ice, you might just get-going/keep-going where all the other so-called 4WDs (Land-Rover/Range-Rover excepted) get stuck. If you live in Minnesota or some such, may with to think on this!! If you like power, and not too fussed about economy, the Outback and the Tribeca have 6-cylinder versions - thirsty but excellent motors. The 4cylinder versions also work. And there's a turbo version of the Forester, XT, I think, might be worth a look. I've driven one of those and liked it.
Faced with similar requirements (grandparents & distance travel) we chose a Land Rover FL2. The latest iteration is called a Discovery Sport. We got a diesel (not sold in US) and couldn't be happier. Zero reliability issues; they've been addressed (unlike Jeep, who are still poor - see JD Powers). An FL2 or Discovery Sport with that excellent (Ford-based) turbo 4cylinder might suit your needs. Most servicing can be done by a Ford dealer if no Land Rover dealer is handy.
One thing to consider (which probably influenced your Mercedes choice) is 'joy of ownership' - feeling that you got the right car, and enjoy ownership. A while back, wife looked at the (Mercedes) Smart car - but the servicing costs totally destroyed fuel economy cost savings. Wound up getting a Honda Fit - which does everything the Smart would have done - and a lot(!) more - and over a year, cheaper to own.