That's not too bad.
I don't have any personal experience of either the C220CDI or W210 E220CDI to be able to recommend them myself. Mine is the first MB I've owned - but it is a great car.
I would consider doing the maths though. Depending on your mileage per year and type of driving you do, you should consider if the cost to change vehicles (what you lose on yours, the potential extra premium of buying a diesel vehicle over the equivalent petrol, the fact that diesel is more expensive etc.) versus the extra cost of the additional fuel you use in yours over a more economical diesel (and how much more economical in the real world are the diesels of the era you are looking), makes financial sense...