Bill Collin

mefferso

The GL is an incredible highway cruiser as you obviously found out on your test drive. I think the overall reliability of GL's is below average although some people have great luck. If you can turn a wrench it's not to bad as that'll save you a ton. Spend some time on searching posts in this forum about the 350 as they seem to be more problematic than the 450/550. If you're in luck, the one you choose will have already had many of the common problems already repaired. If not, you'll know what to expect. My GL450 hasn't been as reliable as a vehicle with under 100k should be but I don't care. Nothing out there in the older used market will give you the same ride, quietness and power combo.

Callisto1

Mine is a 2010 GL350. I occasionally tow a 5000 lb boat or airstream.
Call it repair or scheduled maintenance, all these things usually are required by 100k.
Replace adblue tank because of heater failure, (mine has failed twice)
Oil Cooler seals
Engine mounts
Airmatic front & rear (replace struts at same time)
Timing chain replacement.
I have NOT had the sludging/seized engine, catastrophic failure, but search this forum for that thread and decide for yourself.
Also, they are finicky about low ash oil, and DPF can fail if they don't get it.

cemeek

We had a 2010, and a 2016, and I cannot recommend one without the/an extended warranty. That is unless you're already an experienced late model diesel Mercedes mechanic, in which case go for it, they should be "cheap" compared to other marques.

2010 was CPO with extra extended warranty purchased, was probably a bit better fit and finish build quality overall, and the more reliable one of the two. I estimate it had ~$14,000 of warranty work done over 3 years we owned it, until it was totaled in a rear end accident. Granted that is dealership prices, but still. I definitely recall multiple suspension airbags and pump(s), air mass sensor or whatever diesel equivalent was, 2 separate occasions of oil leaks spotting the driveway, fuel pump, something additional that required some significant top end disassembly, sorry don't recall exactly what (timing chain noise?), crank or camshaft sensors maybe, but it caused check engine light; and some stuff I flat out don't remember. I think we got it with 45k and it made it to 75k miles before it got hit? Had a brake job done out of pocket, pads and rotors up front (maybe all around) that the dealership was surprisingly competitive on - I think 1100? compared to my local independent.

2016 was a new replacement for the totaled 2010. It left us stranded several times with a no-start condition around ~5k miles. It had a passenger side parking camera that kept failing, was in the shop 4 times for that, never remedied. We returned it - not lemon but got trade-in assistance from MBUSA because it qualified - there's more detail on that one here on these boards.

I have to agree though that the diesel is the sweet spot for efficiency and torque - no issues for you pulling a boat. They are also sweet cruisers on the highway. Quiet, comfortable, and don't handle all that bad. The superior ride is evident if you can test drive back to back against American or Japanese equivalents like a Suburban or Sequoia/Land Cruiser.

Despite our experience with the two diesels I'm still in a 2017 GLS550 - just on a 30 month lease with bumper to bumper warranty coverage. Love them, hard to beat these SUVs for ride quality and comfort. And the 550 has some boogie in the butt.

Hope this helps

ddruker

Similar experience here as your other respondents. 2011 GL 350 with 70,000 miles. Use it to tow a large airstream. I would not own it without an extended warranty. I've had closer to $30,000 of covered repairs over the life of the vehicle so far. Same exact stuff as Callisto above plus a few more. It's been in the shop about every four months since new. I just purchased a 2 year extended extended warranty from USAA a few weeks ago as I came off the extended 7 year factory warranty. While I do all of the normal servicing myself, I don't have the time or desire to take the engine apart for the timing chain, oil cooler seals etc which will fail multiple times. Or the suspension airbags and compressor which will also fail etc etc etc. Drives great, just very unreliable and hideously expensive to repair if you use the dealer and pay out of pocket.

Bill Collin

BlownV8

Go with a GL 450. You won't have the issues of the diesel with the exception of the Airmatic and trans valve body but if you buy a higher mileage one it was probably already done. My 450 was more reliable as it aged. Don't be scared of Airmatic. It's not that bad and gives a great ride that automatically adjust the level when you tow.

Ariesfamous

My Indy mechanic gave me 2 pieces of advice before I bought my last car ..

1. No 7 series bmw without warranty
2. No blutec anything

Fwiw