Common problems leading to repairs on Mercedes Benz C-Class vehicles include downshifting issues and faults with door locks. More general problems include lack of interior room and low fuel economy.
Some people have reported a problem with the Mercedes C-Class shifting into lower gears and a loss of power between first and second gear. Another commonly reported problem is door locks repeatedly locking and unlocking.
Puddles and heavy rain can also create a problem for the vehicle. At times, when driving through particularly deep puddles or during intense precipitation, the vehicle shuts down and does not restart. Cold weather can also be an issue, with some owners reporting the engine making a high-pitched noise while being started in low temperatures. There have also been reports of the navigation display either ceasing to function or having a screen that is burned out.
Less-serious problems with Mercedes C-Class vehicles include complaints about space. The rear seats and trunk have been described as too small, especially in the coupes. Also, vehicles built before a redesign have poor fuel economy, with the C300 only managing about 21 miles per gallon. Another knock against the C-Class is a lack of power when compared with rival vehicles.