I have two W251's - a 2007 and a 2012.
First off, I would like to thank you for the detailed reply.
I've got three kids and didn't want another Suburban. Additionally, my wife and I looked at the GL and determined that wasn't as easy to maneuver, park, and that the GL didn't get the mpg of the R.
I have 4 kids (youngest is 9 and oldest is almost 14.
The 2007 we've had since 2014 and the 2012 I bought in 2017. I've put 80kmi on the 2007 and 30kmi on the 2012. Here's the issues I've had in that time:
2007 R350 Gas Starting Mi 72k, Current Mi 156k
2015 - Replaced a single rear air shock - looked as if the other had already been replaced - no charge repair by seller
2016 - Intake manifold replacement due to idler door linkage breaking - dealer quoted $4850 for repair, local specialist shop did the job for $750 with the exact same parts.
2017 - Brakes - shoes and rotors all the way around, brake flush, LOF - local specialty shop $675
2019 - Broken oil filter housing leak caused misfire only at cold start, replaced tensioner, associated timing components, plugs and coils, some internal parts, dealer wanted $6100 to repair paid $1550 to local specialty shop
2012 R350 Gas Starting Mi 44k, Current Mi 74k
2017 - Weird vibration in rear wheel - Dealer suggested we replace rear axle and diff, forgot the quote amount, local shop fixed the problem by moving the wheels around and rebalancing the tires, no charge
2018 - LOF - specialty shop - $65
2018 - Powered trunk latch assembly failure - $412 did the repairs myself
2019 - Parking Sensors don't function properly - no fix yet
What about suspension bushings, control arms, etc.? Any issues with these in either cars?
Here's the deal though, with kids, if you're going to buy one of these cars, be sure and buy the version with the captains chairs in the second row - the three-part bench seat is difficult with two baby seats in the second row because you cannot access the third row as the seats won't move forward to allow access with the child seats buckled in place. The rear seat is accessed by opening the hatch back and having your kid crawl in from that direction. It's not a good solution. So if you want to use the third row, get yourself the version without quasi three way bench.
This is not possible with my kids' ages. My 9 yr old and the 11 yr old will be sitting in the 3rd row if I get the captain chairs in the second row. With the 3-part bench, I am hoping my 11 yr old can sit with her older siblinings in the second row bench, especially since my 11 yr old always suffer from car-motion sickness.
Additionally, the doors are so huge on this car, don't think you can open them in the garage with another car next to you with any sort of ease. I have uploaded a photo which shows this problem. We typically have to back out a car to easily strap two kids in the second row AND insert a kid into the third row.
To be honest, I'm looking to purchase a Mercedes van I haven't decided which version - my wife prefers the $145k AWD Mercedes Van - which isn't too attractive an idea to me.
I do love the R class however, and for some reason I feel like my 2012 is quite a different feeling car than the 2007. They just feel quite a bit different. The 2012 feels lighter and handles a bit better. The interior doesn't feel as quality as the 2007. The 2007 is actually quieter in regards to road noise, the doors seem heavier than the 2012.
These are simply my personal observations, I have no scientific facts backing my statements.
Thanks for the great feedback. I really appreciate it. I have a friend who is an automotive service manager at a "famous" car dealership in Vancouver. He got an R350 as a trade in once and he drove it for a day and hated it. It had the air-matic suspension and he tried all settings and he still could not like the handling. I have yet to test-drive one myself to check. I am not a big fan of air-matic due to the potential service costs, and I would be happy with an R-Class with normal suspension.
He also mentioned that it had terrible gas-milage (~12mpg city). I think this was because it was a trade-in and the previous owner probably hadn't serviced it for a while prior to the trade-in.