GLS Class (X166) Produced from 2016 to 2019

How reliable has been your 2017-2019 GLS 450

Old Jun 11, 2024 | 03:46 PM
  #1  
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How reliable has been your 2017-2019 GLS 450

I found a 2019 nearby with 40k miles for 35k with exterior and interior color I like, it has PREMIUM 1 PACKAGE, LANE TRACKING PACKAGE, ILLUMINATED STAR, ILLUMINATED RUNNING BOARDS.

I am on fence due to reliability.
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Old Jun 11, 2024 | 03:52 PM
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Originally Posted by ruturaj
I found a 2019 nearby with 40k miles for 35k with exterior and interior color I like, it has PREMIUM 1 PACKAGE, LANE TRACKING PACKAGE, ILLUMINATED STAR, ILLUMINATED RUNNING BOARDS.

I am on fence due to reliability.
450 has the M276 3.0TTV6, the most reliable MB engine in the past 20 years.

MB is not as reliable as Honda or Toyota. But in the MB world, the 450 engine is about as good as it gets.
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Old Jun 11, 2024 | 03:55 PM
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Extremely reliable but you want a P3. The upgrades are worth it. Never, ever, ever, buy an MB without the lighting package. You are welcome.
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Old Jun 12, 2024 | 12:22 PM
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Originally Posted by chassis
450 has the M276 3.0TTV6, the most reliable MB engine in the past 20 years.

MB is not as reliable as Honda or Toyota. But in the MB world, the 450 engine is about as good as it gets.
Thank you. What are the common issues one might face? Electronics mainly? How's the transmission?
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Old Jun 12, 2024 | 12:26 PM
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Originally Posted by BlownV8
Extremely reliable but you want a P3. The upgrades are worth it. Never, ever, ever, buy an MB without the lighting package. You are welcome.
Just read on that, it sounds awesome. I will try and find one with it. I really like the blue exterior and brown interior on the one I found, it's 180 miles away from me, I am looking for one nearby that I can test drive and then pick up one that's 180 miles away. I just need to check how child seats fit, seems like GLS is wider in 2nd row than non body on frame SUVs but may be not as wide as full size body on frame SUVS. I think it would be pretty much best handling out of the cars I have driven in the same class.

Last edited by ruturaj; Jun 12, 2024 at 12:27 PM.
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Old Jun 12, 2024 | 05:11 PM
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I just picked up a GLS550 because we are having a 3rd kid and the E63 wouldn't hold a booster, convertible and an infant seat. I already miss that car. They will probably fit tightly in 2nd row, but I also like that the 3rd row has Iso-fix, a lot of other brands don't.
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Old Jun 12, 2024 | 06:10 PM
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Originally Posted by thtguy
I just picked up a GLS550 because we are having a 3rd kid and the E63 wouldn't hold a booster, convertible and an infant seat. I already miss that car. They will probably fit tightly in 2nd row, but I also like that the 3rd row has Iso-fix, a lot of other brands don't.
Even if they fit tightly I think it's still pretty good. My plan is to fit wife and kid in rear for now, but also 2nd seat when we have another kid in future. I need bigger vehicles as parents would be visiting end of the month. 3rd row is also great when in laws visit with kid, so they can be in same row, definitely a great feature.
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Old Jun 12, 2024 | 07:27 PM
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Originally Posted by ruturaj
Thank you. What are the common issues one might face? Electronics mainly? How's the transmission?
MB transmissions are generally...bad. They depend on fluid changes every 50k miles or so to maintain any semblance of acceptability. Hard and clunky shifts are the main complaint. The 9G seems capable of going beyond 100k miles if the oil changes are done.

Engine is pretty bulletproof. Check now and then for cam sensor and cam magnet oil leaks in the wire harness connectors. Widespread issue on M274, M276, M278 and M157 engines.

Suspension, steering, brakes and body are solid. Entertainment and electronics don't have recurring issues. Keep an eye on sunroof drains, taillamp gaskets and rear liftgate gasket to avoid water intrusion and collateral electronic damage. Water intrusion on SUVs is a general MB issue across model years.

Change spark plugs every 40k or so miles. Change ignition coils with every other plug change.

Change all axle and transfer case oils before 75k miles.

Last edited by chassis; Jun 12, 2024 at 07:28 PM.
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Old Jun 13, 2024 | 01:24 PM
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I'm the original owner of a 2017 GLS 450. 82k miles and only recommended maintenance except for rear brakes. Tires are another story, but not terrible. Overall, I'd do it again. Great vehicle, even if it is a bit boring.
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Old Jun 13, 2024 | 01:50 PM
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Originally Posted by chassis
MB transmissions are generally...bad. They depend on fluid changes every 50k miles or so to maintain any semblance of acceptability. Hard and clunky shifts are the main complaint. The 9G seems capable of going beyond 100k miles if the oil changes are done.

Engine is pretty bulletproof. Check now and then for cam sensor and cam magnet oil leaks in the wire harness connectors. Widespread issue on M274, M276, M278 and M157 engines.

Suspension, steering, brakes and body are solid. Entertainment and electronics don't have recurring issues. Keep an eye on sunroof drains, taillamp gaskets and rear liftgate gasket to avoid water intrusion and collateral electronic damage. Water intrusion on SUVs is a general MB issue across model years.

Change spark plugs every 40k or so miles. Change ignition coils with every other plug change.

Change all axle and transfer case oils before 75k miles.
Thanks, that's not bad. I do transmission fluid change on my track car once or twice a year, so 50k is pretty long interval. I will be putting 5-6k miles a year, so probably would not need 2nd flush when I own it.

Would follow the rest as well. Suspension seems to need frequent replacement/repairs as well, are those possible to DIY?

Edit: seems like transmission fluid change isn't a DIY option but still not bad to pay once during ownership
https://mbworld.org/forums/gls-class...hange-diy.html

Last edited by ruturaj; Jun 13, 2024 at 03:09 PM.
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Old Jun 13, 2024 | 01:52 PM
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Originally Posted by redcarrera
I'm the original owner of a 2017 GLS 450. 82k miles and only recommended maintenance except for rear brakes. Tires are another story, but not terrible. Overall, I'd do it again. Great vehicle, even if it is a bit boring.
Thank you for sharing. That's pretty good, I can replace brakes under an hour. Tires are where I don't mind spending money, that to me is most important part.
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Old Jun 13, 2024 | 10:14 PM
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Agree dealer cost to change transmission fluid is not terrible.

Suspension air strut replacement seems straightforward, reading posts on this site.

Brakes are easy, if you have some prior DIY experience.
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Old Jun 15, 2024 | 12:08 AM
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Originally Posted by chassis
Agree dealer cost to change transmission fluid is not terrible.

Suspension air strut replacement seems straightforward, reading posts on this site.

Brakes are easy, if you have some prior DIY experience.
Thank you. How is much is average dealer cost to change transmission fluid?

Saw another thread with Arnott shocks as suggested aftermarket replacement. Pricing is pretty good on them too.

Yes, I have replaced brakes multiple times on different vehicles. So not an issue there.
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Old Jun 15, 2024 | 06:39 AM
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Call 2 dealers in your area for transmission fluid change prices. A few years ago for a 7G the price was in the $600-$700 range. A 9G might use a bit more fluid, and prices have increased. I would guess something in the $700s range.

Last edited by chassis; Jun 17, 2024 at 09:41 PM.
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Old Jun 17, 2024 | 08:34 AM
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Originally Posted by chassis
Call 2 dealers in your area for transmission fluid change prices. A few years ago for a 7G the price was in the $600-$700 range. A 9G might use a bit more fluid, and prices have increased. I would guess something in teh $700s range.
Just paid $1,072.50 back in March.
Service $577.50
Oil Sump 164.00
10 screws 20.00
Fluid 292.00
Screw plug 8.00
Overflow pipe 11.00

Dealer in Raleigh, NC
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Old Jun 17, 2024 | 09:45 AM
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I bought a 2017 550 in Sept 2022 as CPO. One annual service last year. Preformed flawlessly until last Monday when the dash indicated all safety systems were not working. CEL on as well. Local shop diagnosed faulty wheel sensor. Should be fixed today.
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Old Sep 18, 2024 | 11:08 PM
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Originally Posted by ruturaj
I found a 2019 nearby with 40k miles for 35k with exterior and interior color I like, it has PREMIUM 1 PACKAGE, LANE TRACKING PACKAGE, ILLUMINATED STAR, ILLUMINATED RUNNING BOARDS.

I am on fence due to reliability.
I would not be, Mine is 2017 188,000 and still running strong, only ac compressor went, radiator and alternator that’s it. It has been extremely reliable I take it up to Vermont Canada etc, amazing car.
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Old Sep 19, 2024 | 02:51 PM
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Originally Posted by pjw1967
I bought a 2017 550 in Sept 2022 as CPO. One annual service last year. Preformed flawlessly until last Monday when the dash indicated all safety systems were not working. CEL on as well. Local shop diagnosed faulty wheel sensor. Should be fixed today.
Did you recently install a new battery?
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Old Sep 22, 2024 | 03:37 PM
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Originally Posted by ruturaj
I found a 2019 nearby with 40k miles for 35k with exterior and interior color I like, it has PREMIUM 1 PACKAGE, LANE TRACKING PACKAGE, ILLUMINATED STAR, ILLUMINATED RUNNING BOARDS.

I am on fence due to reliability.
Just one data point here, but we bought our '19 GLS450 new in the fall of 2019 and it has been nearly flawless. We're currently at 61k miles and have done the following with only 2 minor warranty claims. With the exception of one service done at the dealer, I've done all the work in my garage without much difficulty. I would certainly buy another X166 and may even look for another low mileage 166 when we're through with our current ride. As y'all know, there is absolutely nothing about the GLS450 that is exciting, but if you're looking for a quiet, reliable, comfortable, luxurious family mover appliance that won't break the bank, the X166 is hard to beat.

3/1/20 (10k mi) - oil/filter
2/24/21 (18k mi)- oil/filter, cabin filter, brake flush

Warranty - cracked wood trim on driver's door card

11/16/21 (28k mi) - front discs/pads, oil/filter
6/29/22 (38k mi) - oil/filter
2/4/23 (45k mi) - wipers

Warranty - driver's knee airbag

4/19/23 (47k mi) - rear pads, new tires
6/4/23 (49k mi) - oil/filter
8/20/23 (52k mi) - brake flush
4/15/24 (55k mi) - trans filter/fluid, oil/filter


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Old Sep 23, 2024 | 08:43 AM
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Originally Posted by cyk
We're currently at 61k miles and have done the following
What! No tires?
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Old Sep 23, 2024 | 10:42 AM
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Originally Posted by John CC
What! No tires?
Nope, installed new Crossclimate 2's @47k mi. Prior to that, I was swapping winter & summer tires.

As a side note, for those in wintery/slippery climes, I used to run Blizzaks in the winter but grew weary of the biannual tire/wheel swap ritual and decided to try the Crossclimate 2's year round. I can confidently say there is no need to run a dedicated winter tire any longer. The CC2's work great in deep snow/ice/slush in hilly/mountainous terrain (we're @8k ft in the Rockies). As a huge benefit, the CC2's are super quiet and are rated to last 60k miles!
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