djay

Hi all,
I recently got the B Service done on my '14 GL450 at 35k. Upon delivery after service, the mpg dropped drastically from 14 to 11. I initially thought it was temporary as it could be due to reset of data and the vehicle is in learning mode. However even after driving 1000 miles, the mpg has not yet gone back to original.

Has anyone experienced this? Could this be due to a tuning/programming change at service? Any suggestions how can I revert back to the previous state?
Thanks,

jacobsung

I had the same hunch with '13 GL350. But no way to prove that.

You may want to check if your brake pads are sticking.

jlim

I have the opposite experience. At 26k, I brought it in for a 'B' service (I got the '14 GL450 at 16k miles). Since I saw this post, I took the photo of my morning drive. It shows 21.9mpg for a 9 mile commute.

Since reset (I've only reset it once when I bought it), it is around 16.8mpg overall in the 8-9 months I've owned it.

djay

That is truly amazing Jlim. Also your average speed for this trip was just 35mph. You must be hell of a driver

What mpg does your GL start with in the morning?

I will take it back to the dealership to adjust the tune. I use 91 Octane and got a light foot on the pedal at all times.This last service they did the brake flush, maybe that is what is causing the mpg to drop (Brake pad/caliper sticking).

jlim

This was my morning commute from home to work.

I could take either local roads or highway to get to work. Difference is only about 1.5 miles difference. I'll take the highway tomorrow and see what the mpg is.

djay

Hi Jlim,
When you turn on your GL in the morning, what is the starting mpg at which your vehicle starts its day? Mine is 11.6 and as I drive it gradually increases to a max of 12.5?

mtm

just as another point of reference - 2013 GL450, mixed highway and local roads, average speed 24 MPH, 15.6 mpg

EDIT: this morning from start it showed 11.7 mpg and after 3 miles in town driving showed 12.3 mpg at 16MPH average

mtm

jlim

Ok, I see what you mean about the starting MPG. You can see in the first photo, when I startup the car, it is showing --.-. Car is in reverse as I am backing out of the garage.

When I switched to Drive, it shows 11.7 mpg (last night after I got home, it was at 15.6mpg). So, the starting MPG I don't think means much.

I took the highway this morning to work. I got 17.2MPG in the end. It was 11 miles (2 more than using local roads), 37MPH (2mph faster than local), but it took me 19 mins (3 minutes longer than local). And MPG was 17.2 (4.7mpg worse than local).

I always drive to work via local roads (less cars in the morning), but HW heading home (faster). I can't try this again tomorrow as I'm headed a different direction but will report back on Mondays' morning commute if I can achieve a repeat of 21.9mpg.

mtm .. your coffee cup symbol is showing all the time? Mine only appears when it thinks I'm being distracted in my driving.

mtm

yes, the cup is always there. Probably different cluster programming - yours has the lights mode, which mine doesn't.

jlim

This morning's commute.






Not sure why the huge discrepancies from what you guys are experiencing. But this is just the morning commute with light traffic. My overall MPG since reset last Sept remains around 16+MPG.