There are examples of 2009-2011 production years for the mentioned money on the market with the only gasoline turbo engine 1.8, but in three variants of forcing - 156, 184, and 204 horsepower (up to 2009, inclusive, the engine was equipped with a compressor). All presented variants are equipped with rear-drive and classic automatic transmission.
The main problem with the engine is the timing chain drive, which is subject to stretching. It is amazing, but according to the regulations, this mechanism is designed for the whole service life, which is unreal in our conditions, of course. If suspicious noises are coming from under a hood, it is worthy not to delay replacement. Together with a chain, not to disassemble it twice, it is necessary to also change clutches on camshafts, which can fail. Their imminent end is also reflected by the increased noise of the engine. The turbine, oddly enough, is very reliable and can fail only due to irregular oil changes.
As with the A- and B-Class, the C has a weak drive belt, which needs to be replaced as early as 50,000 miles. The thermostat fails, and it is also mandatory for the C-Class to warm up in winter. The point is that due to the features of its design the crankcase ventilation system freezes, and as a result, oil can get into the intake system unnoticed (there is no pressure sensor in the car). In neglected cases, it is possible to catch a wedge.
Mercedes C-Class is equipped with two automatic systems: until 2010 - ancient and therefore almost unkillable 5G-Tronic 5-speed gearbox, which has been replaced by more difficult and capricious 7-speed.
The box and the engine have a common cooling system, and therefore it is worth watching it twice: clogged radiator or running antifreeze is the reason to check and clean the whole system. Overheating is one of the frequent problems with a gearbox, and it especially concerns a seven-speed. Besides, the brave guys often exposed the box to high loads, arranging drift-raids, starting from a stop-light and other races.