I thought I'd put my experience with running 2nd hand Mercs on. I've had 5, 2 c220 diesels from 2000 vintage thought to my present 2012 slk 250d. The first 220 had my most expensive repair with £1000 going on some electrical fault. Apart from that the slk needed a £500 indicator stalk and a headlight which I know the garage doing the mot did. Apart from that it's been the usual tyres, brakes, servicing and usual mot things, wipers, bushes etc. I can't say Mercs have been more expensive to run than the other cars I have had and apart from the clk 320 petrol which drank like a camel but was great to drive they have been very economical. The clk went 5 years ago for the slk and is still running around on a w plate.