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Old 01-07-2009, 01:32 PM   #1
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Car Feels Like I'm Braking When I'm Not...

This might just be my lack of knowledge of cars, but when I'm driving my car and let it coast as I approach a red light, the car slows down fast (without my foot on the brake) almost as if I am breaking. Is that normal? I didn't experience anything like that with my first car (a Jeep Grand Cherokee). I have my car in "C" mode since I'm not at 1k miles yet, although I will be after tomorrow!

So basically, I'll drive up to like 40 or 50 mph, then I'll let go of the gas and as my car slows down, it slightly jerks as it slows down, almost like i'm tapping the brake.

Any input is appreciated.
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Old 01-07-2009, 01:50 PM   #2
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Is it simply the auto trans downshifting?
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Old 01-07-2009, 01:55 PM   #3
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I think it is, but it's not smooth, I can actually feel it jerking a little as the car slows down....just wondering if that's normal.
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Old 01-07-2009, 01:57 PM   #4
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Although I have a manual, the time I have spent with the autos left me thinking they were relatively smooth. If you have an '08, have you updated your software?
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Old 01-07-2009, 01:59 PM   #5
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I have an 09, only 3 months old with 960 miles on it...
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Old 01-07-2009, 02:29 PM   #6
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i believe this is quite common in 7G-tronic transmissions

Sometimes your in the middle of a gear, it is about to upshift but then u slow down so it is in-between gears as it downshifts giving u that feeling

for example, when im in the process of stepping on the gas, but then suddenly let go, it will do this. its rather hard to explain but i according to the shop foreman this is normal.

if u hear otherwise let us know.
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Old 01-07-2009, 03:04 PM   #7
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This makes no sense to me.

I'm a big gasoline saver, or try to be. I sometimes coast a *long* time before red lights, I mean, several football fields I'll cancel cruise and just coast. I have no jerking sensations or anything.
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Old 01-07-2009, 04:55 PM   #8
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This is one reason I choose manual transmission on my C220 CDI.
At least I do the shifting and I can do that very fast when needed.
I read and hear of too many problems about automatic gears.
I will always prefer to have control of the gear and decide myself when to downshift or upshift when I make knots on four lanes.

Last edited by eminnet; 01-07-2009 at 06:59 PM.
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Old 01-07-2009, 09:08 PM   #9
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Hey everyone, thanks for the replies. I might ask my dealer about it next time I go in for a car wash. Mac911 - I definitely feel something, so maybe I just need someone else to drive it and see if they agree. Thanks again.
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Old 01-08-2009, 04:10 AM   #10
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My automatic C300 does the same. Feels like you downshifted when you take your foot completely off the gas pedal.

I asked if it was normal and the dealer in the US said it was... I didn't like it until I got to Germany and I find that it's actually very handy to have the car slow down when you take your foot off the gas, especially since most of the roads over here are winding... It helps on brake wear.

I don't notice it anymore when I'm driving, and I don't really see it as a problem. Just more of a quirk.

PS: That slight jerk is probably a downshift in your tranny as you're slowing down. If you're driving in sport mode your car will try to keep the best gear for acceleration. Try it again and when you feel the jerk, watch the tach and you'll probably see a slight blip in your RPM's as your engine catches up with the downshift. I noticed it doesn't do this as harshly when in comfort mode.

Last edited by 08w204; 01-08-2009 at 04:13 AM.
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Old 01-09-2009, 01:09 PM   #11
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Thanks 08, I'm glad to see that it isn't something that is wrong with my car. I guess I'm just not used to it, which I can tell because i'll let off the gas when I approach a light and I end up at almost a stand still way before I was expecting it
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Old 01-09-2009, 11:57 PM   #12
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Maybe if you place it in neutral when you approach a stop you'll be able to determine if it's the brakes or the transmission causing the sensation. Eventhough everyone says it is normal, it make you feel better knowing whether or not it is an issue with the brakes.
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Old 01-11-2009, 02:52 AM   #13
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Originally Posted by killacam7479 View Post
Thanks 08, I'm glad to see that it isn't something that is wrong with my car. I guess I'm just not used to it, which I can tell because i'll let off the gas when I approach a light and I end up at almost a stand still way before I was expecting it
I still don't understand what you describe, because I also let up on gas, or cancel cruise control very very far back from stop lights, and I have no such issue. Sure, I mean the speed drops naturally, but not too fast, especially between 60 and 40 it drops quite slowly.

Is this at lower speeds?
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Old 01-12-2009, 09:14 PM   #14
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my 2009 C350 has this issue as well. it is a brake pad saver technique and usually happens in the low gears, 1-4. I dont like this about the 7G because it wont let me save as much as as i would like. however, its programmed into the car and theres nothing i or you can do about it.

this is especially evident when going down a hill. the car will not speed up as much as it should, and automatically uses engine braking a lot earlier than other cars.
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Old 01-13-2009, 01:26 AM   #15
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Quote:
Originally Posted by joshg1001 View Post
my 2009 C350 has this issue as well. it is a brake pad saver technique and usually happens in the low gears, 1-4. I dont like this about the 7G because it wont let me save as much as as i would like. however, its programmed into the car and theres nothing i or you can do about it.

this is especially evident when going down a hill. the car will not speed up as much as it should, and automatically uses engine braking a lot earlier than other cars.
I don't follow your statement, you don't like the brake pad saver technique but you would like to save more? What would you like to save more? To me this isn't even any brake pad saving feature but it is gasoline saving feature, when the engine is braking, fuel injection is completely cut out. If the engine was running idle, it would spend some fuel. If you wanted to save more fuel, it is better to brake with the engine. A pity if this brake force is too high for your taste.
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Old 01-13-2009, 10:22 AM   #16
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I believe he may be referring to gas?

I checked again this morning, kind of hard to because there is a ton of snow on the ground, but if I'm driving 50 mph, and I let go of the gas as I approach a stop, around 35mph, I can feel it slowing as if I am braking. This looks like it is in line with JOsh's explanation.
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Old 01-15-2009, 02:05 PM   #17
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yes i was referring to gas. lol. i meant that it wont let the car coast for as long as you would like. this wastes gas because then you have to keep on the accelerator again. well this seems like a common issue.
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Old 01-15-2009, 02:21 PM   #18
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This does not seem to be the case with the 5 speed auto on the 220CDI. It seems to free wheel well.
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Old 01-17-2009, 03:00 PM   #19
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Originally Posted by killacam7479 View Post
This might just be my lack of knowledge of cars, but when I'm driving my car and let it coast as I approach a red light, the car slows down fast (without my foot on the brake) almost as if I am breaking. Is that normal? I didn't experience anything like that with my first car (a Jeep Grand Cherokee). I have my car in "C" mode since I'm not at 1k miles yet, although I will be after tomorrow!

So basically, I'll drive up to like 40 or 50 mph, then I'll let go of the gas and as my car slows down, it slightly jerks as it slows down, almost like i'm tapping the brake.

Any input is appreciated.
I own a 2007 C280 4Matic and my vehicle does this as well. I noticed this when I test drove the car and mentioned it to the salesman who was riding in the back seat. He said this is completely normal. He had some technical term for it but I can't remember what it was. I wouldn't worry about it too much!
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Old 01-18-2009, 03:58 PM   #20
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Yep, noticed the exact same problem in my 09 c300 sport. I almost forgot about it until i saw this thread.
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Old 01-21-2009, 01:41 AM   #21
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My '08 C300 Avantgarde Sport does the same thing. I actually like it. It does, however, take some getting used to.
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Old 03-29-2009, 07:32 PM   #22
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Hi Killacam, I have the same problem/issue with my C280 as well. Whenever I let my foot off the gas, it feels like the car's engine braking. Asked the dealer and they said it's normal and its part of the car's feature. I also test drove another C280 to compare and true enough, that other car has it too. Looks like it's just a trait of our cars we'll need to live with. Maybe there might be a software update for it or something in the future.
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Old 03-30-2009, 08:34 AM   #23
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Mine does the same thing.

Notice the tachometer when its slowing down, it'll jump to higher rpm as it downshifts.
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Old 03-30-2009, 09:10 AM   #24
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yea i have the same issue...

it feels like a downshift... but it does jerk a bit...

i recently (friday) got the update... i hope... dunno if they actually did it... so ill see if that did help.
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Old 04-01-2009, 07:58 PM   #25
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Guys. These cars, both 5 & 7 speed have lock up clutches on the torque converter so they can't freewheel. They have locked up drive from just after pull away until just before you bring them back to a halt.

This increases efficiency & reduces torque converter losses to virtually zero. So on trailing throttle you are running against compression.

If the GB is not smooth. Have the dealer flash the latest 7G software. It's being constantly updated. The 5 speed is a mature box but it too sometimes benefits from a software reflash.
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Old 04-01-2009, 07:58 PM
 
 
 
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