Amazed
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GLS 450 (2022), EQE SUV 350 (2025). GLS 450 (2007)
Amazed
Drove from Chadron Nebraska to Fort Dodge Iowa today on US20. There was a strong wind behind us, the road was basically smooth, straight and flat most of the way, we held a steady 65 mph on cruise, and overall we dropped about 1000 feet in sea level elevation. There was zero traffic and almost zero stop and go. Result? I got just over 30 MPG on my 2022 GLS 450. Couldn't believe it, such excellent performance.
Last edited by Scott Schmidt; Jun 17, 2026 at 08:00 PM.
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Current/Last 5-years:GLS;G70;Alpina B8;X7;Accord. Sold:X7,TeslaS;S560;S550,X5;530e;L.Navigator;LS460
The inline-6 is a phenomenal engine. I can get high 20s too. Even the V8, it is very efficient and mbenz knows how to make highway cruisers. These SUVs need those big engines, and it is already proven that they can still be so efficient. The engineering behind them is just awesome for a car of this size. Each time I see how other cheap economy brands going with 4-cylinder engines on suvs to save cost and to squeeze out every single MPG possible out of, in exchange to terrible and cheap drive feelings, I really laugh, and at same time feel the need to thank Mbenz for making a u-turn and keeping the inline-6 and V8 across the luxury line up. I hope we can continue to enjoy the 6-cylinder and 8 cylinder engines for as long as possible and that emission regulations and certifications (or cost cutting measures) won't impact at least the luxury rides. There is still room for cheaper economy suvs with other brands to use small engines; but I hope that Mbenz can keep the 3-row SUVs like the GLS/GLE isolated from all of that.
Last edited by S_W222; Jun 17, 2026 at 08:09 PM.
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I agree... How many other real full size 3-row SUVs on the planet can offer us all of that in one SUV? Not many.... Can barely count them on one hand maybe. I am GRATEFUL!. I am even more grateful when I travel and end up in other economy rentals; makes me appreciate the difference even more.
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2021 GLS450
Great highway vehicle
Hello,
I bought my 2021 GLS450 at the end of January. In February I took it on an 800 mile round trip. I got around 27 mpg and averaged over 60 mph. On the highways I cruised at ~72mph. I could easily travel 600 miles on a tank of fuel. At the end of the trip I felt good- relaxed and comfortable. My back was a little stiff from sitting 4 hours but otherwise i felt great. The car was quiet, comfortable, fast, and efficient. Like you, I was amazed at the performance.
Tonight I leave on another trip, this one will be about 700 miles. I'm taking my new to me 2013 SL550. It will be interesting to compare the two vehicles.
Barry
I bought my 2021 GLS450 at the end of January. In February I took it on an 800 mile round trip. I got around 27 mpg and averaged over 60 mph. On the highways I cruised at ~72mph. I could easily travel 600 miles on a tank of fuel. At the end of the trip I felt good- relaxed and comfortable. My back was a little stiff from sitting 4 hours but otherwise i felt great. The car was quiet, comfortable, fast, and efficient. Like you, I was amazed at the performance.
Tonight I leave on another trip, this one will be about 700 miles. I'm taking my new to me 2013 SL550. It will be interesting to compare the two vehicles.
Barry
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Current/Last 5-years:GLS;G70;Alpina B8;X7;Accord. Sold:X7,TeslaS;S560;S550,X5;530e;L.Navigator;LS460
Hello,
I bought my 2021 GLS450 at the end of January. In February I took it on an 800 mile round trip. I got around 27 mpg and averaged over 60 mph. On the highways I cruised at ~72mph. I could easily travel 600 miles on a tank of fuel. At the end of the trip I felt good- relaxed and comfortable. My back was a little stiff from sitting 4 hours but otherwise i felt great. The car was quiet, comfortable, fast, and efficient. Like you, I was amazed at the performance.
Tonight I leave on another trip, this one will be about 700 miles. I'm taking my new to me 2013 SL550. It will be interesting to compare the two vehicles.
Barry
I bought my 2021 GLS450 at the end of January. In February I took it on an 800 mile round trip. I got around 27 mpg and averaged over 60 mph. On the highways I cruised at ~72mph. I could easily travel 600 miles on a tank of fuel. At the end of the trip I felt good- relaxed and comfortable. My back was a little stiff from sitting 4 hours but otherwise i felt great. The car was quiet, comfortable, fast, and efficient. Like you, I was amazed at the performance.
Tonight I leave on another trip, this one will be about 700 miles. I'm taking my new to me 2013 SL550. It will be interesting to compare the two vehicles.
Barry
The only feature I wish it has for road trips is to allow lane keeping assist while towing!. For some reason it does not allow that feature when towing, but not many SUVs allow that anyway for safety reasons.
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'21 AMG53 wDPP & ARC, 19 GLC300 - Former-03 C240,2 ML BlueTecs,20 GLE450 E-ABC,15 Cayenne D,17 Macan
Yeah, same here, we put 10s of thousands of miles in just 2 years!…. We will hit 100K miles in no time if we keep it long enough. GLS is a true family hauler for road trips.
The only feature I wish it has for road trips is to allow lane keeping assist while towing!. For some reason it does not allow that feature when towing, but not many SUVs allow that anyway for safety reasons.
The only feature I wish it has for road trips is to allow lane keeping assist while towing!. For some reason it does not allow that feature when towing, but not many SUVs allow that anyway for safety reasons.
For some reason it only enables the hitch alignment view after the 7 pin is connected, so I have to plug in before I hitch. Strange logic.
I don't think I'd use Active Steering Assist while towing (I tow a 27' travel trailer and various other trailers). Things can happen really fast with a trailer. I don't use Active Lane Keeping ever.
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Hi @chassis . I always appreciate to read your perspective and realism without any normalization or owner-driven narcissism that we sometimes see around. I know you love the brand, but you are always realistic at the same time. In this case, however, I feel that the inline-6 deserves the credit here. Even under these conditions, for a massive truck like this, I can’t name any SUV with the same size and weight that can easily get 30 MPG, but maybe am wrong. The SUVs that get close to that are the cheap korean/japanese economy rentals with rental vibes, and they barely get there with small engines. In all cases, I really want to give Mbenz credit for showing no BS transition to 4 cylinder engines, and keeping their inline-6 aw the smallest option on flagships like the GLS. I get to drive some of these rentals, and test-drove some new 3-row models around, and I really struggle and laugh as I see OEMs throwing 4 cylinder engines just for the sake of cost-cutting measures and chasing emission goals too. U’d have to pay me to own cars like that, so I appreciate mbenz for the inline-6. I think small 4 cylinder engines can be fine for an economy cheap rental use case, but the GLS is still treating us nicely with a very responsive engine that also sounds nice, and still a V8 option too. In sport mode, I really love how the engine responds. No regen stupid feeling non-sense, just a nice ICE engine with 48V EQ boost. I think Mbenz is still doing fine in this department, and I am NOT excited for the day when emission and cost-cutting measures will force even flagship luxury owners to settle for cheap small engines. That’s the whole point… good gas mileage combined with luxury nice engine feel.
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For the X7, I never had the inline-6, all three of them where M50i and m60i trims. I had however the X5 with the inline-6, and it would also get me 27-29mpg or so. I don’t recall how the coast mode worked but was likely off cause I coded it to Comfort_Plus which is different from eco-pro.
Last edited by S_W222; Yesterday at 04:42 PM.
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2024 S580
At the end of the day a vehicle of the caliber of the GLS should always have a 6 cyl engine at least. Personally if I were to buy one for myself I wouldn't even get the 6, I would get the V8. For a family vehicle the 6 is fine. There isn't anybody I can think of that is selling a vehicle of the GLS' caliber with a 4 cyl engine...
There are cheaper vehicles out there that have 4 cyl power like the Lexus TX and the Palisade and Telluride...but those vehicles are not on the same level as the GLS or X7.
What amazes me is that the GLS450 gets mileage that really is very similar to those 4cyl powerplants, even the Toyota hybrid 4.
There are cheaper vehicles out there that have 4 cyl power like the Lexus TX and the Palisade and Telluride...but those vehicles are not on the same level as the GLS or X7.
What amazes me is that the GLS450 gets mileage that really is very similar to those 4cyl powerplants, even the Toyota hybrid 4.
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'21 AMG53 wDPP & ARC, 19 GLC300 - Former-03 C240,2 ML BlueTecs,20 GLE450 E-ABC,15 Cayenne D,17 Macan
My Cayenne DIESEL got 29mpg on road trips. My GLE450 got 32 on the same trips; the GLE350 (4cyl) yhat I had as a loaner for 30 days and 1,000 miles got 30, and my AMG53 gets 24.
I found out that if I only go 5 over I get 28 with the AMG 53. On the reverse trip I set the Distronic at the actual speed limit and I got 31. (But that WAS with a tailwind, no traffic and down 1,500 ft in elevation.)
These SUVs push a lot of wind.
Last edited by mikapen; Yesterday at 05:43 PM.
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2024 S580
When you think about the performance and the economy these engines return its really amazing.
In my S580 doing 80 on cruise control with mountains 1/3rd of the trip I get near 30MPG, in a 500hp V8.
In my S580 doing 80 on cruise control with mountains 1/3rd of the trip I get near 30MPG, in a 500hp V8.
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Doesn’t matter, because in the GLS, when drive assist features are on with adaptive cruise control, the GLS never “cruises” or turns the engine off while adaptive cruise control is on. So, I still got good MPG even without coast mode under eco being functional.
For the X7, I never had the inline-6, all three of them where M50i and m60i trims. I had however the X5 with the inline-6, and it would also get me 27-29mpg or so. I don’t recall how the coast mode worked but was likely off cause I coded it to Comfort_Plus which is different from eco-pro.
For the X7, I never had the inline-6, all three of them where M50i and m60i trims. I had however the X5 with the inline-6, and it would also get me 27-29mpg or so. I don’t recall how the coast mode worked but was likely off cause I coded it to Comfort_Plus which is different from eco-pro.
