That's so true : I went from a W126 500SEL , which returned mid to low twenties mpg , but never missed a beat in my 5 years ownership , and other than one road spring , a couple of ball joints and a couple of bits of welding for the MOT , never needed more than routine DIY servicing , despite annual mileage of 20,000 or so . My various W201 , 123 & 124 cars were similarly reliable , with the biggest jobs being a heater matrix on one 190 , a water pump on another , and an engine swap in the third and current one due to CHG failure - all these jobs done by myself on the driveway .
Anyway , after five years of happy W126 ownership ( at which point rust was getting the better of it ) with the only downside being big fuel bills , I decided to try a 'cheap to run' diesel ; our first diesel car , other than a cheap diesel W124 I had bought previously for SWMBO , more of an opportunist purchase since a friend offered it for a bargain price than a planned one , and after a bit of initial fettling on a car that had been lying unused ( servicing , glow plugs , tank filter ) it turned out to be a good car if somewhat ponderous .
Anyway , I did some research and consensus seemed that the 270 was the best engine , and I picked up a 2003 C270CDI Avantgarde SE estate on 115K miles for £3K , which at the time compared to others for sale seemed a decent price .
To give its due , it drove smoothly , returned around 50mpg throughout my two years ownership , but was plagued with problems , few of which were in my DIY comfort zone , and the garage bills amounted to more than the purchase price , so the fuel savings were completely wiped out .
I'm now back with older Mercedes cars , swapped the 203 for an R129 , which I had to sort out the results of neglect by previous owners but am now on top of with a good , reliable car and 30mpg economy I can live with and 12000 miles covered since purchase in May ; and the 190 I bought for £250 while still running the 203 and had a year's pleasurable motoring , covering 5k in it as a second car , before deciding to embark on the engine swap from 1.8L to 2.3L , new engine now in and running sweetly , new tyres and numerous other service items done , towbar fitted , brake upgrade to do before putting back on road and car still owes me well under £1K thus far , but looking forward to same or better fuel economy than the SL .