BENZ BOSS DP

Folks, I am seeing about ~28-30 in the city with avg speed of ~35 while on the highway, I am only getting ~26 MPG with avg speed of 55-60. I recently drove about 500-1000 miles and on a cruise control, gears are constantly switching between 7 and 8 and that is eating up MPG. I went to MB dealer and they are saying it is perfectly normal and no issues. However, on a cruise control... mostly emtpy road, why is the gear switching between 7 and 8? Why I am getting only 26 MPG?

Anyone else has this situation?

Extremeengineer

I wish I was getting anywhere near those numbers. My morning drive consists of 25 and 35 mph roads, no extended periods at a constant speed, and I get an actual 19, yes 19 mpg. I never remote start or let car “warm up”, always have auto stop on, and usually I am only occupant. On the highway here if you aren’t doing at least 80 you are a road hazard and so I get about 25 on the highway. Mileage sucks, very disappointed. My 911 gets better mileage. My commute is the ideal commute for an EV, after driving my mother’s Volvo XC40 Electric, I am seriously considering trading in for one.

Vladimir Livson

I am getting 25mpg with mixed driving. When driving to work very early in the morning, I average between 30 to 36 mpg (depending on the season) per commute. However coming back (crawling in NYC traffic) I get 20 to 25 mpg. 2 Years overall average is 25mpg. As a comparison driving same route with 1.5L Turbo C-RV I get around 27 mpg on average vs 25 mpg GLB, however I get better highway averages with GLB (up to 36mpg vs 34mpg on C-RV per highway trip).

P.S. Season and how you drive does make a difference on MPG. I always get better MPG in Spring and Fall, vs Winter and Summer when either Heat or AC is blasting. Driving in "Sport Mode" will reduce your MPG as well.

homerbrew

I am averaging about 25 for city driving and closer to 35 for highway driving, especially when driving on level highways. Overall so far since we received ours we are averaging 29.8 mpg overall after driving about 16k miles. We had one leg of a trip where we reached 39 mpg on a highway.

diggs718

Even when I was driving around slow as hell to break in engine I didn't get anywhere near that gas mileage. Are you getting this from the app on your phone or just your calculations? The car will adjust somewhat to how you drive, even in eco. For example my daughter loves for me to stomp it when getting on the highway so even in eco my GLB started downshifting and responding to accelerator much faster in 3rd and 4th gear for a day or two. I tend to drive a bit heavy but my mpg over 7000 miles is barely over 26. My last trip I averaged 25 mph over 23 miles and got 20.8 mpg.

Timmins13

Hello, I am a new owner of a pre-certified 2022 GLB FWD. I tried ECO mode but didn't find that it gave me better MPG vs. Comfort mode. It seemed ECO mode was holding D7 longer on the highway vs. COMFORT. What do others think about ECO mode? What does it do to improve MPG? Thanks.

Vladimir Livson

I also found that Comfort mode had better MPG's than ECO, even while sitting in traffic.

Odd Piggy

My 2-bits:
We do mixed suburban-highway driving. We pay more attention to miles/tankful than mpg. We’re getting 450-480 in comfort mode. That’s around 28-30 mpg in a FWD model. A 4matic is heavier and has more drivetrain load, so I would expect 1-2 mpg less (420-460/tankful). In our driving eco doesn’t seem to make any difference on the GLB. It might help if there’s a lot of city driving.

diggs718

What PSI you got in the wheels? Something seems off if that low. Maybe not worth your time, but have you tried setting up your own profile and just setting it to manual mode? Not sure if this is available on all packages or not, but I've found I know better sometimes on which gear to be in than the car. Especially on slower roads like you described. I doubt shifting yourself could account for that much MPG unless again something is wrong with the vehicle. I've got similar gas mileage when I was idling a lot and driving around in sport mode like a crazy person. Maybe your fuel in the area is some super high ethanol blend or something? I felt like Michigan had some of that but wasn't bad like Indiana. Anyways whatever it is something seems off on your vehicle compare to my heavier 4-matic version that only drives around Atlanta so speed varies from 3-110, but usually my average speed when I look at trip info is the low to mid 20s. Even my last trip which was all rush hour and slow shows my average speed at 12 mph and MPG at 22.1. I do feel like depending on the wheel size you have, PSI can make a good bit of difference. Maybe try putting yours toward the middle range of the listings in the fuel door if you haven't already decided to trade it for the Volvo.

Timmins13

Recently I have been driving in ECO mode when in stop and go traffic.
I'm not sure if it helps fuel economy, however to me it seems to be reducing the jerkiness of the DCT when starting out and stopping.
I think it is because ECO mode usually starts off in D2 (vs D1 for Comfort).

Any thoughts on this?

Odd Piggy

The harsh 1-2 upshift has been mentioned in other threads. When my 2021 GLB250 was in for other service they applied a transmission software update that made 1->2 much smoother.

Timmins13

Thanks for the info on the transmission software dealer. I will ask service about that.

tbirdvet

Remember this is a dual clutch trans and will not be as smooth as a normal auto but it sure can shift fast!

Timmins13

Thanks. I actually really enjoy driving the car. It is an easy car to drive, and very comfortable.

Dgoins1

I agree we get about 2 week’s going roughly 45 miles round trip M-F to work in ECO mode. We stick with it with turning auto stop off saves us gas and great MPG

Timmins13

Thanks for your info on ECO Mode.
Does ECO mode turn off Auto stop?
I notice in certain situations when coasting in ECO mode, the D light turns green. Does anyone know what that means?

Dgoins1

No you have to manually turn it off by pressing it under the start button. It means If you've selected ECO mode, when running on two cylinders you'll see the current gear (e.g D6,D7) symbol change to a green D. This would typically occur when coasting downhill.

Timmins13

Info appreciated.

Vladimir Livson

Sometimes the car will temporary turn Auto Stop off (the Auto Stop will turn yellow). Typically when the car just started and it's cold out, or driving in heavy traffic and car cycled through Auto Stop on/off too many times.

jlk211

I agree I love it