I find the quality to be poor for a car with the 3 pointed star.
1- Interior plastics are cheaply made and assembled as noise levels increase everyday.
2- The passenger door handle does not close properly and is always in the open position.
3- The drivers seatbelt retracter does not retract.
4- The ambient lighting works half the time. dimming no longer works.
5- The fuel gauge is about as accurate as the weatherman. I must now keep tank above 1/4 mark.
6- The tranmission gear shifter is so loose it feels like a Hyundai.
7- The transmission slips at times. Usually it is very smooth shifting but around town, it lacks logic. It never shifts when you expect it.
8- The trunk needs a powerful slam to close. Latch, not properly assembled.
9- The traction control lights just came on last week and I have yet to have it repaired. And the list goes on.
I had a 2005 Infiniti G35 which I turned in when the lease was up. Overall a very good car. At first the Mercedes C 300 impressed me with its style and seeming quality. On par with the Infiniti. I drove it around and found the smaller engine sufficient enough to get around but not even close to the engine of the G35. The salesman talked me into the smaller engine because he claimed it was much better on gas than the C350. Back then premium gas (which the MB requires) was $3.30/gal so efficiency was a concern. The options look nice but are expensive if you're not careful. I upgraded to the bigger AMG wheels which made the car look stunning but ride quality suffers a bit. Handling got better as did braking performance. The seats all around are excellent. The nav system takes time to get used but its OK. Not the most logical but it does the job.
Again, I find the quality to be very poor for a car of this caliber. My list of items that have failed is longer in one year and 19k miles than all the problems I had with my Infiniti G35 for 3 years and 60k miles.
The worst part though, is the fuel economy- I average 15 MPG combined city/highway. It's appaling and worse than any other car I have owned including a 1984 Mercedes. It also should be noted, the C300 drinks oil at an alarming rate, or roughly 1 qt of oil per 2k miles.
Overall I can't recommend this car to anyone. There were several people I have talked to about their 2008 C classes and all had similar problems. For the price I paid it's expensive- I could have gotten a Cadillac CTS for less money and its rated a much better car. I already test drove it on saturday and found it to be a superior car to this. I never thought I would say this about Cadillac but it is better designed and engineered than my Mercedes C class. Plus the Cadillac supposedly gets better gas mileage (owners reporting 21 MPG average), it has a lot more power (307 HP vs 228 HP) and interior space in a slightly larger exterior dimensional package. This week, I'm selling my Mercedes on eBay and will buy the CTS. Good luck.
Pros- Sleek body turns heads with optional 19 inch sport rims, excellent seats, good brakes don't fade on highway, smooth cruiser at 100+ MPH.
Cons- Fuel mileage is terrible, interior quality is terrible, reliability is terrible, slow compared to other luxury cars, looks sporty but drives like a 1980's Yugo.