While driving on a city street in stop and go traffic, I noticed that the car was not shifting gears. The tachometer would rev high but the vehicle would not accelerate in accordance with the revolutions. Once traffic freed up from a stop and go 20 mile/hr the car would not shift gears and remained in limp mode. I brought the car to my mechanic who confirmed it was a transmission problem. The current quote to replace the 7 speed 722.9 transmission is $2800 parts and labor.

- Garden Grove, CA, USA

Moments after exiting the freeway and reducing speed at around 35 mph my car did not accelerate and continue as it would in neutral. Family in the car panic and for my fortune light traffic on an usual busy street. The check engine light did not turn on at the moment of days after the incident. A week later without a warning the vehicle engine light turn on and lost speed in the freeway. This incident could easy cause my family and other drivers a fatal accident and preventable injuries. I have found many similar incidents describing what happen to me and its awful that nothing is being done to fix it. I will contact my local representative and senator to demand action and a formal investigation about this issue.

- Daly City, CA, USA

On Nov 27, 2013, I was in the los angeles area on highway 14 traveling around 70 mph on the highway w/ many cars and my speed dropped to around 50 mph in spite of my foot downing the accelerator to the floor. I had to turn on my emergency lights and move over to the slow lane for safety. Returning home that same day on the same freeway, the car would not accelerate or transmission would not downshift to compensate for the uphill on the freeway in spite of stepping down on the accelerator- again I had to flash my emergency lights on and move to the slow lane. There is no sensor light on the dashboard for both incidents. My mechanic reported it will be hard to diagnose the transmission problem since there is no sensor light on. On Nov 29, 2013, I traveled to las vegas and the transmission repeated the decelerating incident and failure of the accelerator to increase engine or transmission speed. This is dangerous.

- Las Vegas, NV, USA

Suddenly during normal driving conditions, when trying to accelerate the car is very sluggish and the RPM are very high. This happens without warning increasing the potential for a crash. The problem is normally rectified temporarily by restarting the vehicle.

- San Diego, CA, USA

Periodically the car would lose acceleration and rpms would be high and the vehicle would jerk when I tried changing gears. As I change gears from park, reverse or drive, the gear shift jerks and I am unable to accelerate past 20 mph no matter how much pressure I place on the gas. : extreme loss of acceleration up hill and the steptronic (+/- shifting) did not work... (I could only go 35mph when every one else was going 70mph up hill) when I traveled on a flat surface with no inclination my car worked fine, I then decided to put it on neutral while traveling at 65mph...when I put it back in drive it did not pick up the gears it just continued as if it was in neautral. I had to pull over and shift it into park...as I shifted form "D" to neutral it shifted fine, but then from neutral to "R" the car jerked...from reverse to "P" it jerked again and shifted hard. I then shifted again to reverse, neutral, and drive thus the car jerked and did a hard shift with knocking noise and would not drive. I shifted to neutral again and shut the car off. When I turned it back on it shifted smooth and I drove off without any problem. Took it to a repair shop and received P0717/P0718 fault codes and something about the valve body. I was also told that it was an transmission internal speed sensor issue. There is something faulty with the design and operation of this model year transmission and losing power and being able to only go 35 mph no matter how much you press the gas on the interstate or heavy fast moving traffic is extremely dangerous. Mercedes Benz is aware of this problem as many owners have complained but they will not institute a recall.

- San Antonio, TX, USA

The transmission internal speed sensor failed indicating that the valve body needs replacing. The gears are not shifting properly and get stuck. I have to pull over and turn the car off for about 10 minutes to let everything reset and then ok to drive. If I do not stop and turn car off and put it into park with engine still on and try to shift back into drive it is a hard shift and then the car will jerk. I saw on line all the complaints with the same problems for the C230 sport.

- Santa Ana , CA, USA

I was driving my vehicle on the highway during morning rush hour when I noticed that the car would not accelerate over 35 mph. I moved the car off the highway and stopped at a red light. Once I stopped the car it would not accelerate at all when I stepped on the gas. I had to put the car in park and then move it back to drive to get the car to move. The car would jump and lurch forward when I shifted gears. I drove the car directly to the dealer. The Mercedes dealer told me that there was a problem with the software and that the software would need to be updated. I went to pick up my car after the "software " was updated ($1,700 cost) and drove the car about 10 miles when I noticed that the check engine light had come on. I took the car back to the Mercedes dealer to let them know the check engine light was now on. The Mercedes dealer told me I have a defective balance shaft that needs to be repaired. The Mercedes dealer ask me if I had kept up the oil changes on the car. I told the them that I had. The Mercedes dealer told me that I have to pay $2,500 just for them to take the engine apart and that the total repair will cost around $6,000. I just purchased the car in July 2010 ( 14 months ownership) with about 19,500 miles on it.

- Austin, TX, USA