I purchased the car at 3 years old with 32k miles as a replacement for a Honda Accord 1.8 Sport. It was bought for both business and social use as at the time I was doing anything up to 30k miles per annum, mainly motorway miles, so this was to be a comfortable, lazy, economical replacement. I'd always wanted a Mercedes and believed all the hype about it being solidly built, "German Engineering", high residuals due to slow depreciation and the ability to eat up the miles with few problems. The car we chose has full leather, rain sensing wipers (which have never "rain sensed"), auto lights, full electric memory seats, split "auto" climate control, trip-tronic auto gearbox (Sport & Comfort modes), front and rear parking sensors, on-board computer with all the bells and whistles.
First the good news - it is wonderfully comfortable to drive any distance you like at whatever speed you like. Set the cruise control and just let it go. Up to 4 can travel in relative peace, comfortably and the sound system auto adjusts as background noise increases and as the driver I have the assurance that there's adequate power reserves should I need them.
The not so good news is that once off the generally smooth motorway surfaces and onto A, B and urban roads and it all gets very trashy. The suspension jars from one pothole to the next, the 255 section tyres follow the camber and wheel ruts, the interior creaks and rattles like it's about to disintegrate and when stuck in urban traffic jams the proximity of other cars, cyclists and/or pedestrians set of the parking sensors, usually making you jump out of your skin and just sometimes, off the brake pedal. Economy is just about acceptable - Mercedes claim 42 mpg overall (combined driving) but the on-board computer flatters to deceive (it claims I have averaged 46 mpg since purchase). On long motorway journeys it will report over 50 mpg (I have seen 62 mpg on it) but the sums on the spreadsheet don't support it after the fill-up.
While I'm on about the not so good, I have to mention the "driver aids". Traction control. It is so obtrusive that it even cuts in on bone dry roads. You try to accelerate hard and unless you are in a dead straight ahead line with all four wheels then forget it, the onboard computer cuts the power and a big warning light flashes at you from the centre of the speedo. Then if you have to brake hard (which happens) and then want to get back on the power, most of the time the computer will have interpreted the heavy braking as being "collision avoidance" and has cut the power from the engine and thereby creating a potentially "serious incident" while you wait for those few seconds it takes to realise that it was wrong and that it is safe to re-apply the power.
The bad news - and it is very bad. Apply what I've just said about the "driver aids" to what happens in bad weather (like the last winter). Drive onto compacted snow or ice on a very slight incline and the engine power will be cut as the wheels loose traction, apply the brakes and the ABS won't let the brakes be applied so you coast out of control until you either stop or hit something. Fail to apply the parking brake and the next thing is you are rolling back down from whence you came, again unable to stop. That's very scary.
As I write the car has covered 103,800 mikes, so I've done 70k miles in just under 4 years, and I'm grateful that my reliance on this car have subsided (I now commute mainly by motorbike to my new place of work). Like I said earlier rain sensing wipers have never "rain sensed". In the middle of a motorway journey coming back up the M1 I got a "SRS complete system failure" message from the on-board computer (diagnosed by the dealer as a faulty message of the airbag system having been deployed in the driver's door). Next, the central locking system failed due to the "ingress of water" into the door mounted controller. Various suspension arms, joints, bushes and linkages have failed and been replaced along with all 4 springs (the front 2 at the 100k service, the rear 2 just 2000 miles later) with the breakages all at exactly the same point of the spring ( of a turn from the end of the spring). And despite all this attention the suspension continues to knock. The electric seats have a mind of their own - they do remember the memory settings, but the head restraints sometimes do and sometimes don't go up and down when expected/asked. The auto (as in "always on") climate control is as predictable as a shopping trolley as to whether it will blow hot or cold, gentle or a gale.
The interior looks do not give any hint that the car has done 100K plus miles, but the exterior paintwork - oh dear! Compared to other cars I have owned that have done these sorts of mileages (Ford Granada 2.8, 2 Vauxhall Astras, a Rover 800, Toyota Carina e, Toyota Rav4 and Honda Accord) the paint quality is terrible and despite choosing a car in "Brilliant Silver" which should show stone chips the least, I'm sorry to report that the front end reveals this car as a motorway car in the worst possible display of quality and "German Engineering". The paint appears to be woefully thin and marks badly with the slightest impact from winter road salt, grit and stones.
Having bought from a car supermarket, I initially tried using my local franchised dealer (Inchcape) for servicing but after one particular incident and the 80k service I gave up and now get my servicing done by my son (a BMW trained Senior Technician) or one of the local independent Mercedes specialists. But even going down this route has seen the spend-o-meter shoot above £2,500 (excluding tyres, for which it has a voracious appetite - especially fronts which struggle to get to 15k before dying). The "incident" that put the nail in the "franchised dealer servicing" was a quote to replace the o/s/f headlamp when the self-levelling mechanism stuck. That'll be "£1,257.00 plus fitting plus VAT to you sir!" No it wasn't - it was 5 minutes stood out in the freezing cold and snow with a 14mm socket and a can of WD40. The mechanism has stuck again twice since and I can now do the job in under 2 minutes.
The original intention was to keep the car for a minimum of 5 years, however, I've decided I've had enough. The two big, wide opening doors are a pain in car parks, access into the rear seats is clumsy and the constant aural abuse of my ears by the bings, bangs, boings that are seat belt sensors, parking sensors, parking brake sensors, rear door (hatchback) open sensors, water bottle low level sensor (all accompanied by a vivid illuminated dashboard and graphic computer display). These things might be necessary for Americans, but, I'm not American and I sometimes want to do things "my way" which just happens to be contrary to those that have been programmed into the on-board computer. And I hate the American style foot activated/applied item. In summary, there are too many sensors and not enough sense. Mercedes have lost the plot when it comes to build quality and ownership has been the biggest disappointment of my 54 years on this planet. I will never own another Mercedes and urge anybody thinking of buying one to invest their money elsewhere (unless they are American, in which case they will ignore this advice anyway).

I've got a 2002 auto Mercedes-Benz C220 CDI. I bought it in 2003 at 22K miles. Agree with some comments out there about the sluggishness of the auto diesel that it doesn't pull away quickly but once it does, it is fast! It is a head-turner for sure but much more; the boot is extremely spacious and once you put the seats down you can load the whole world in it... For my job I used to take sample Polystyrene pallets to customers and I can fit a 1200x1000 mm pallet in the boot even an estate or saloon won't take it! On an average motorway journey, I get up to 55mpg. The sunroof makes it extremely airy. BUT the negative is the cost of servicing! Labour cost is £100 ph and when you analyse the bill, you see something like £120 worth of parts/materials etc and £480 is labour cost! How many hours did you work on the car? Dealers and the customer services are generally arrogant as if you didn't buy the car with your money, it was given/donated to you by them or something and you should be grateful and feel obliged? Driver seat is uncomfortable, cup holder is not good,foot brake doesn't release sometimes! ESP needed replacing, electrics not right as I've been having to change the brake light bulb almost every 2 months but no other problems so far, and it is very reliable, now that I've got over 100K miles on the clock. My husband has a BMW 120d. In terms of drive, the 1 series is better than my Mercedes but the spaciousness, the panaromic sunroof & sexiness of the Mercedes cannot be matched.