9-Gtronic in petrol GLC 250 is a PITA

[andynpz]

The transmission in my GLC250 is far too ready to change down a couple of gears, with any increase in throttle pedal, no matter how small or how gently applied. This makes for a very jerky and un-relaxed driving experience. I could live with it if it was only when in Sport or Sport+ but it's almost as bad in Comfort and Eco which seems contrary to me.

Example; Approaching an A-road roundabout at 35-40mph in 5th Comfort - no traffic so continue at say 40 mph and plan modest acceleration back to 60mph as we leave the roundabout. Transmission remains in 5th while off the throttle, but will downshift to 4th as we transit the roundabout, then, as we exit the roundabout, we find that we cannot accelerate without the transmission downshifting to 3rd or 2nd. Remember there are 9 gears, so 4th isn't even half way.

We have owned 2 CLK320s, an SL350 (R230) a C63 and a CL500 MBs, plus Audi, Range Rovers, 2 X BMWs and I have not experienced this irritating and unnecessary downshifting anytime you go to accelerate. It is spoiling my driving pleasure right now as I try to avoid it by super-gentle throttle demands.

Can a gearbox be remapped? Or re-flashed by a dealer? Or can anyone suggest a cure other than changing my driving style to "drive it like you stole it" ?

Any other GLC250 owners out there?

 

[Blobcat]

I found the 9G in my E220 to be the best auto I’ve deiven, yes it took a little more time to get to 9 and wouldn’t always stay there but the rest of the time I’d no idea what gear it was in without looking at the display.
Not sure what’s going on with yours

 

[Botus]

some 9G boxes destroyed themselves during magazine reviews

I'd take out another one and see if its the same as yours.... the 9 is supposed to have very smooth changes... if there's a difference, I'd start with merc software updates and if that doesn't fix, carry on moaning till they fit a new box

but remember Merc like to make their own gearboxes but don't actually know what they are doing. a modern BM box by ZF is light years more advanced and much better - so you can't expect a merc one to be similar

all these stupid numbers of gears are really for emissions and narrow powerband tractor engines... 6 is plenty for a decent petrol engine

 

[thebiglad]

The transmission in my GLC250 is far too ready to change down a couple of gears, with any increase in throttle pedal, no matter how small or how gently applied. This makes for a very jerky and un-relaxed driving experience. I could live with it if it was only when in Sport or Sport+ but it's almost as bad in Comfort and Eco which seems contrary to me.

Example; Approaching an A-road roundabout at 35-40mph in 5th Comfort - no traffic so continue at say 40 mph and plan modest acceleration back to 60mph as we leave the roundabout. Transmission remains in 5th while off the throttle, but will downshift to 4th as we transit the roundabout, then, as we exit the roundabout, we find that we cannot accelerate without the transmission downshifting to 3rd or 2nd. Remember there are 9 gears, so 4th isn't even half way.

We have owned 2 CLK320s, an SL350 (R230) a C63 and a CL500 MBs, plus Audi, Range Rovers, 2 X BMWs and I have not experienced this irritating and unnecessary downshifting anytime you go to accelerate. It is spoiling my driving pleasure right now as I try to avoid it by super-gentle throttle demands.

Can a gearbox be remapped? Or re-flashed by a dealer? Or can anyone suggest a cure other than changing my driving style to "drive it like you stole it" ?

Any other GLC250 owners out there?

i DROVE AN F-TYPE auto RECENTLY and it had 8 or 9 gears and it was always fannying about changing gear. It did the changes quite smoothly so it wasn't jerky but I hated the fact that no matter how I drove it, it would never stay in a 'cruising' gear - preferring to try and optimise the efficacité of the drivetrain. I much preferred the ZF 6 speed in my S-type.

I sometimes think the development of stuff on cars is more marketing-driven than ownership pleasure.

 

[Botus]

its purely emission driven

 

[Craiglxviii]

its purely emission driven

No, it isn’t. We have done this to death. It’s driven by a fairly complex series of performance targets of which emissions plays one part.

 

[ajlsl600]

i DROVE AN F-TYPE auto RECENTLY and it had 8 or 9 gears and it was always fannying about changing gear. It did the changes quite smoothly so it wasn't jerky but I hated the fact that no matter how I drove it, it would never stay in a 'cruising' gear - preferring to try and optimise the efficacité of the drivetrain. I much preferred the ZF 6 speed in my S-type.

I sometimes think the development of stuff on cars is more marketing-driven than ownership pleasure.

yr bang on pal, that and trying to manipulate the fuel/emission figures . more gears , more tech,more hassles ..simples

 

[Botus]

No, it isn’t. We have done this to death. It’s driven by a fairly complex series of performance targets of which emissions plays one part.

Ok how about this
emissions 50% (which for the sake of 3 year olds squabbling I included fuel consumption)
marketing claptrap 50%

 

[Craiglxviii]

Ok how about this
emissions 50% (which for the sake of 3 year olds squabbling I included fuel consumption)
marketing claptrap 50%

If only it were that simple... it’s something like this. There are about 1100 or so individually measurable aspects in a car which can relate to its desirability, of one form or another. Some of those form part of legal requirements (Eu6d now for diesels), some form part of marketing fluff (custom exterior trim colours or paint), while others form hard (Vmax) and soft (steering response, active trace control) performance.

Those 1100 scores group together into about 40 categories, which then group into 12 or so different zones.

Dependent on the grade and powertrain of the car model in question those 1100 targets are set (against a competitor basket of 5-6 other models, or legal requirement) and then weighted. The weighting is carried on at category and zone level.

What you end up with is a series of scores normalised across each other due to the weighting that gets stuck on a radar plot. That then allows the Chief Engineer to look at a category that’s failing target and see why. Maybe the door opening effort is too great for Arab customers (it usually is) so he needs a different check link sticksion for that market. It also allows one category or sone to be compensated for by other performance targets within it. Perhaps the door check link can’t be changed but a power tailgate can be added, which brings the Closures category overall score upto it’s combined target. And so on.

So, emissions overall point to two target areas. One is legal compliance, otherwise the car is unhomologatable- look what happened to Mitsubishi. They didn’t record legal compliance properly on 300 cars and it killed them, they’ll BRINT within a decade (Be Renault In No Time). Another is owning & operating costs, which means things like VED & fuel efficiency. Call it Ownership Cost. Dependent on the make & model, they’ll be weighted differently, so the weighting on a Micra at a sticker price of £16k will be much heavier than a GLC250 with a sticker price of say £50k, the logic being that a customers towards the affordable end of the market will place more emphasis on road tax and pence per mile than those buying D/E segment premium big cars.

That’s it in a nutshell.

 

[malcolm E53 AMG]

As said take it back and complain, the bigger the engine the less gear changes so with the 9spd 250 engine it will hunt for the right gear in some situations, this wouldn’t bother me but if the changes are jerky it would. Does the vehicle have air suspension which I think accentuates harsh shifting. I would certainly complain and try another car, although my son’s eclass 220d 9spd shifts seamlessly

 

[umblecumbuz]

Dang - and it used to be just NVH!
Ain't progress complicated.

 

[Craiglxviii]

Dang - and it used to be just NVH!
Ain't progress complicated.

And do we spec NVH by grade? Or just petrol/ diesel? Performance scoring of NVH is a thesis in its own right!

 

[flowrider]

Logically the more gears you have available the more gear changes there will be. If you think it is excessive then I would see what the dealer can do, maybe a software update is available.

 

[Steve@Avantgarde]

Going back to the op for a potential fix.

I would say that there maybe a software update to be done to either the engine or the gearbox. You haven't stated how many miles are on it yet, but it could be in an adaption phase learning the driving cycles of your journeys and style which means it will do funny things to the shift while the software stores, logs and compensates.

Don't take this the wrong way but sometimes our driving styles also have to change slightly.

 

[Botus]

If only it were that simple... it’s something like this. There are about 1100 or so individually measurable aspects in a car which can relate to its desirability, of one form or another. Some of those form part of legal requirements (Eu6d now for diesels), some form part of marketing fluff (custom exterior trim colours or paint), while others form hard (Vmax) and soft (steering response, active trace control) performance.

Those 1100 scores group together into about 40 categories, which then group into 12 or so different zones.

Dependent on the grade and powertrain of the car model in question those 1100 targets are set (against a competitor basket of 5-6 other models, or legal requirement) and then weighted. The weighting is carried on at category and zone level.

What you end up with is a series of scores normalised across each other due to the weighting that gets stuck on a radar plot. That then allows the Chief Engineer to look at a category that’s failing target and see why. Maybe the door opening effort is too great for Arab customers (it usually is) so he needs a different check link sticksion for that market. It also allows one category or sone to be compensated for by other performance targets within it. Perhaps the door check link can’t be changed but a power tailgate can be added, which brings the Closures category overall score upto it’s combined target. And so on.

So, emissions overall point to two target areas. One is legal compliance, otherwise the car is unhomologatable- look what happened to Mitsubishi. They didn’t record legal compliance properly on 300 cars and it killed them, they’ll BRINT within a decade (Be Renault In No Time). Another is owning & operating costs, which means things like VED & fuel efficiency. Call it Ownership Cost. Dependent on the make & model, they’ll be weighted differently, so the weighting on a Micra at a sticker price of £16k will be much heavier than a GLC250 with a sticker price of say £50k, the logic being that a customers towards the affordable end of the market will place more emphasis on road tax and pence per mile than those buying D/E segment premium big cars.

That’s it in a nutshell.

thanks for writing that, for me it should be simpler
make sure its legal then make it drive properly - shouldn't need to care what others are doing

 

[Steve@Avantgarde]

thanks for writing that, for me it should be simpler
make sure its legal then make it drive properly - shouldn't need to care what others are doing

Because the motor industry is one of the most simplest industries out there isn't it....

 

[Craiglxviii]

thanks for writing that, for me it should be simpler
make sure its legal then make it drive properly - shouldn't need to care what others are doing

That approach presumes that there is no competition for your product. That CAN be true but it’s really rare. The original Land Rover, Golf Mk.1, Beetle and Qashqai are all case studies in market breaking designs as they all had zero competition when they launched.

Look how many crossovers there are now. 18 at last count with VW in the game. Qashqai sales peaked at 360k in 2016, they’re now at 240k and still falling as increased competition lowers its market share.

 

[Botus]

I get worried when customer clinics start to influence how cars are made

on BMs there used to be proper heating controls with one slider for feet, one for face and one for screen, you set each one in one position when you first got the car and never touched it for the life of the car.

then we got women involved... who of course don't want dry skin, so face level vents are now seen by the marketing men as the devils spawn. And you end up where we are nowadays, with either feet and face OK but the screens misted up, screen and feet OK but cold hands … next we got car manufactures' inventing one warm hand and one cold hand, by messing up the centre air vents (with a different temp to the outer ones), I presume for some imaginary heat soak that is actually only on one side of the car at any one time (so any temp differentiation is just a mistake). Thus we end up with everyone normal now has to have one hand and arm cold plus either, cold feet or misted screen... which ultimately means the new focus, the new 3 series and all Mercedes need to be scrapped as the face level vents are in the wrong place

then of course we can wonder what the engineers were thinking without women's help.

On both cars and bikes some halfwit at BMW hasn't worked out if its set up for sporty driving why not just re-enable the safety features if an owner then sets cruise control and put it back to back how he set it when its off... No, they just disable cruise from working instead - so you either park the car and walk coz its less stress! or spend half an hour not looking where you are going twiddling knobs and menus back and forth so the car drives normally (which of course is far safer)

and....if it was just about money why add a redundant button on the dash

my last one has this wind up the air con to max feature which then didn't revert air flow settings back to how you had it beforehand, and so you manually have to reconfigure everything - so you had to remember to never touch the button

 

[Craiglxviii]

The heater controls thing is all down to Cost Reduction...

 

[rorywquin]

Not sure if the 9 speed comes with different ratios dependant on the engine it is bolted to.

Many factors to consider but broadly speaking, less HP & torque = more gear changes.

The GLC 250 has a similar kerb weight to my SL but a lot less power...

I find the 9speed (in C mode) almost unnoticeable in my car and the auto shifting in S and S+ is really nice. The paddle (auto mode) and M shifting is a huge improvement over the 7 speed that I had in my SLK350.