OK, maybe you guys are getting sick of this, but I am just looking for answers of anybody who has had the same experience as I am having.
I bought a CPO 2020 GLC63 AMG with 12K miles in 10/3/2022.
10/27/2022 my CEL came on and there were 4 codes, 2 current for inlet air system leakage and 2 stored for coolant temperature and camshaft position.

The CEL went off a few days later and I did a couple of 0-60s on my Dragy to see how it was running, it did a 4.15 and 4.23 which if I include rollout like all the magazines is anywhere from a 3.85 to 4.00, close to manufacturer and magazine times.

The car has been in to the dealer twice since then as the CEL came back on.
Each time the CEL was cleared after a software update and a coolant flush, both times I was told the problem was solved.

The CEL is back on again.
The dealer does not want the car back, they sent me a bulletin saying Mercedes is aware of the situation and there is currently no fix, but that this does not affect performance and is safe to drive.

The disturbing thing is, since the car has been to the dealer, whether the CEL is on or off the car will not do any better than a 4.50-4.60 0-60 (4.24 to 4.33 with rollout).
Obviously it does affect performance.

Apples to Apples, this is showing a 35+ hp deficit since the dealer supposedly fixed the problem each time.

They have never addressed the intake leakage, only the coolant issue.

I called the dealer I bought it from, they are 60 miles away in another state, to far for me to travel for service, they said they will see about picking the car up and that they will make it right?







.

 

I can appreciate your frustration as I've seen many of your posts on this forum about your vehicle's troubles since owning it. Unfortunately, the X253 sub is a ghost town. Even if it were more active, I truly don't think anyone on here would be able to help - you're best bet is to take it to your dealership and tell them to tell you whats going on.

Having said that, there are a lot of factors that can affect a 0 to 60 time and saying my car will do 0 to 60 in 3.X seconds in the context of talking about differences in the tenths of a second is largely not a good indicator of a vehicles performance over an internet forum. Environmental conditions, the biggest being ambient air temperature - cold air is more dense therefore a twin turbo engine is generally going to perform better in cold environments. But cold environments generally have cold roads. What about your tires, are you running stock and what is the tread quality and are the tires warm when measuring your times? What is the best quality fuel available in your area? Are you running 93 octane? Are you using launch control? Supposedly the GLC 63 ECU has something like 50 requirements (various temperature measurement requirements, steering wheel alignment, zero slope, etc.) that need to be validated before the vehicle will launch. Mileage, wear and tear, gross weight of your vehicle with options, how much fuel is in your tank, do you have a dirty air filter, I mean the list goes on dude. It's impossible to align all the variables that affect tenths of seconds when we're talking about that short amount of time and distance.

My point is, base lining your vehicle off 0 to 60 times against what a magazine says or even peers here is a poor measure of your vehicles performance because there are too many variables. Does it sound like something is going on? Yeah obviously because your ECU is telling you that... and I could be wrong, but I'd hazard to guess that it'll be impossible for anyone here to know without getting under the hood. This is the job of your dealership's technician team. If you still think the experts who deal with this kind of stuff every day are wrong, consider going to an independent dealership or getting it dyno'ed?

 

I posted on the c63 forum and got my answer.
As for 0-60...
I am very aware of how to do it and have done it many times with many cars.
My GLC63 runs are always on 93 Sunoco in cool to cold air, tires are New Pirelli all-seasons at mid to high 35-37lb pressures (not as soft as summer tires, but good or better in cool to cold air (35-50 degrees) than summer tires, I use all-seasons on my 911 Turbo S and get 2.91 (2.72 rollout runs on similar all-seasons). My best 60ft time with the Mercedes is a 1.98, way off. The Porsche does a 1.63 on similar tires.
I could lower the tire pressure to lower 30s and it might help, but the car is not spinning as is.
I do a race start launch at 3500 rpms, I always make sure operating temp and trans temp are in the white range.
As for dirty air filter, the car was CPO's at 12K miles, if that was not at least checked or replaced then they did not CPO it properly,

Point is, the CEL is on and the car's 0-60 should be closer to published times than it is. For example, a 4.2 (3.9-4.0 with rollout) would be an acceptable time if the car was making normal power.

 

The point I'm trying to make is that there's a tremendous amount of evidence to support that 0 to 60 times published by the manufacturer, media, or real world aren't useful indicators to diagnose issues with a vehicle's engine performance profile within the tolerances you're currently baselining you're measurements against. And deducing that a factor of X.X seconds deficit correlates to a XX horsepower deficit - it's not even remotely that simple. Your GLC 63 could be producing 150 horsepower over what the manufacturer advertises but if your torque curve, gearing, timing, ECU that controls all of the above, etc., aren't performing as intended, you'll wouldn't sniff the *** of a Camry to 60 mph. But regardless this is your thread. I hope the answer in the C63 forum resolves your actual (or imaginary) issue and please keep us posted for archival purposes.

 

Quasi butt dyno aside, can you share the bulletin or know the code/ID of it so we can look it up?

I'm just curious. Seems ridiculous that an issue that causes CELs is known and deemed unfixable (temporarily at least).

 

Let's put it this way, they way people rave about how fast the GLC63 is, supposedly comparable to a Trackhawk which I have also owned and was very impressed with the performance.
If my car is running correctly, I can't believe all of you think this slow of a car is impressive. This leads me to believe my car is performing subpar, as noted on the C63 forum, it is most likely in a soft-limp mode.

If you look up my other thread you will see the whole issue and all of the codes.
Here is the Bulletin MB sent me.

Car definitely needs a Thermostat, MB service did not even bother to do the job as they said they would as it is to labor intensive.
The dealer picking the car up tomorrow will do that and hopefully check in to the cam magnets which may be producing the other codes.

 

Dealer picked up my GLC63 and dropped me off a GLB250 as a loaner.
I now know my car is messed up, this little GLB250 has way more snap when you hit the throttle than my GLC63.
Don't get me wrong, it is not faster, but throttle response is immediate and snappy, my GLC63 is soft and does not kick down and accelerate with the same urgency as the GLB250.

If they tell me my car is fine and still runs like it does now, it will be sold asap, but I am sure they will not say that.

 

Something seems way wrong. Mine would run 3.6's all day long on stock files via Dragy and 2.9 on my E30 tune. It's a really quick car.

 

That is what I am saying, it has no snap. Feels soft on kickdowns and has no throttle response.
Once moving it accelerates OK, but definitely not responding to immediate throttle input.

 

The service department called me today and they confirmed the car is not running right.

They pulled all the codes and are:

1 - Replacing the thermostat
2 - There is a boost pressure leak and they are going to fix that also.

 

Finally, something is being done to your car to fix the problem. let's hope that it works.

 

They said that is what they plan to do, but they will know more as they get in to it.
They wanted to let me know that obviously it won't be done by tomorrow.
I told them just get the car right.
I am using their brand new GLB250, so I know they will get it done as quickly as possible.

 

Nothing really to add to this discussion, other than I, too, am a new GLC63S owner whose previous vehicle was a 2018 Trackhawk. I didn't track (officially or otherwise) the Trackhawk and haven't tracked the GLC63S, so my experience with both is just seat of pants, but so far I consider the performance of my GLC63S is pretty much the same as my Trackhawk. The main difference, IMO, is that the Trackhawk felt very raw and primal whereas the GLC63S feels more sophisticated and refined, i.e. the Trackhawk felt faster because of its "personality" (brash, in your face, American muscle) v. the GLC63S (highly engineered, precise, European sophistication). It may well be that the GLC63S is a tenth or two slower 0-60 than the Trackhawk but that's not a big deal to me. I loved the Trackhawk (and would still be driving it but for a weird convergence of a nasty collision, stupid insurance company tricks and once in a lifetime market conditions that made it worth more - unrepaired! - than what I paid for it) but am very happy so far with the GLC63S.

 

My Trackhawk was a 2018 and was plagued by the same problem some Hellcats had, it would detect too much air going in to the engine and go in to limp mode and not go over 55mph.
It was fixed 3x and Jeep said one more time and they will buy it back.
Not wanting to go through the whole ordeal again, I traded it for a Range Rover for my wife.

I do like the feel of the Mercedes better, but the Trackhawk was also a very nice vehicle, the gas mileage was brutal, even worse than the Benz.