Which one to own for long haul ownership




The M278/M157 V8 is developing a reputation for piston scuffing requiring engine replacement.
Transmissions seems to have approx 150k mile life expectancy.
Body and chassis are solid.




I have 2 choices right now one with a v6 and one with a v8. The only difference is on the V8 it has ventilated seats and the options are just the same. Wont be towing bit will be loading the truck to the gills with people or gear occasionally. Not sure what to expect on V8 gas consumption but if it close to what I get on my '14 ML350 which is around 19-20 mpg on highway on fully load I would consider the V8. The trick is would the engine last forever like 7-10 years.
I have 2 choices right now one with a v6 and one with a v8. The only difference is on the V8 it has ventilated seats and the options are just the same. Wont be towing bit will be loading the truck to the gills with people or gear occasionally. Not sure what to expect on V8 gas consumption but if it close to what I get on my '14 ML350 which is around 19-20 mpg on highway on fully load I would consider the V8. The trick is would the engine last forever like 7-10 years.
Both are great vehicles. Quit worrying about reliability, you’re buying a Benz, you’re going to spend money regardless! Might as well get the better vehicle ( A CPO GLS550 with 1 year CPO warranty and email Jeff Jackson JJackson@MBLouisville.com for the best price you’ll find on an additional 2 year CPO warranty extension giving you 3 years of total coverage ), and enjoy that Bi-Turbo V8 with an underrated 516 lbs ft of torque!!
I own both a 14 ML350 and a 17 GLS550. You’d be surprised gas mileage is close on highway!
I have 2 choices right now one with a v6 and one with a v8. The only difference is on the V8 it has ventilated seats and the options are just the same. Wont be towing bit will be loading the truck to the gills with people or gear occasionally. Not sure what to expect on V8 gas consumption but if it close to what I get on my '14 ML350 which is around 19-20 mpg on highway on fully load I would consider the V8. The trick is would the engine last forever like 7-10 years.
Yes the V8 is fun. And it guzzles gas and is likely to have scuffed cylinders at high mileage. If those are objectionable to you, skip the V8.
Agree with changing transfer case and front and rear differential oils. Change the serpentine belt at approx 100k miles although MB does not specify to change it. Consider changing upper and lower rad hoses between 100k and 150k miles if you own the vehicle that long.
MB transmissions are barely adequate in most respects. Not bad, however not good. 150k miles for a 7G-Tronic seems when things start going south. I haven’t read a lot about the 9G, it’s still relatively new in the grand scheme of things. The 7G fails in the torque converter, speed sensors and conductor plate (hydraulic solenoid valves). The 9G has yet to show signature failures because of its relative newness.
The V6 has zero difficulty towing and hauling max payload. I have loaded my 3.5L with boat trailer, bikes on the roof, luggage and passengers and it’s a great machine. The 3.0 TT will do even better. Zero concern from a towing and hauling point of view with the V6.
Last edited by chassis; Dec 25, 2021 at 12:19 PM.




Both are great vehicles. Quit worrying about reliability, you’re buying a Benz, you’re going to spend money regardless! Might as well get the better vehicle ( A CPO GLS550 with 1 year CPO warranty and email Jeff Jackson JJackson@MBLouisville.com for the best price you’ll find on an additional 2 year CPO warranty extension giving you 3 years of total coverage ), and enjoy that Bi-Turbo V8 with an underrated 516 lbs ft of torque!!
I own both a 14 ML350 and a 17 GLS550. You’d be surprised gas mileage is close on highway!




Yes the V8 is fun. And it guzzles gas and is likely to have scuffed cylinders at high mileage. If those are objectionable to you, skip the V8.
Agree with changing transfer case and front and rear differential oils. Change the serpentine belt at approx 100k miles although MB does not specify to change it. Consider changing upper and lower rad hoses between 100k and 150k miles if you own the vehicle that long.
MB transmissions are barely adequate in most respects. Not bad, however not good. 150k miles for a 7G-Tronic seems when things start going south. I haven’t read a lot about the 9G, it’s still relatively new in the grand scheme of things. The 7G fails in the torque converter, speed sensors and conductor plate (hydraulic solenoid valves). The 9G has yet to show signature failures because of its relative newness.
The V6 has zero difficulty towing and hauling max payload. I have loaded my 3.5L with boat trailer, bikes on the roof, luggage and passengers and it’s a great machine. The 3.0 TT will do even better. Zero concern from a towing and hauling point of view with the V6.
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We have the lighted star and the fancy Mercedes puddle lights. Is that the night package? If so, it's "cool".








Blue with night package is a no go. Blue looks better with the silver trim.




Blue with night package is a no go. Blue looks better with the silver trim.
Same concerns about reliability. It seems unlikely MB would build a new model with a smaller, slower engine of there were not a reason.





