General Comments:
Got a year from this car pretty much trouble free, except for the front shocks breaking, THEN
Xmas 2009 the car broke down, ending up at a local "official network dealer". 2 weeks later a bill for £1504. I thought I had a new car, how wrong I was.
Long story cut short, my car had a new turbo fitted as well as the valves being done. My car came back to me, and the first thing I noticed was how slow it was; the garage had re-flashed the ECU unit once the new turbo was fitted, PUTTING THE CAR BACK TO ITS FACTORY SETTINGS. The re-flash took the remap off of my car; a total waste of money (£300) and "since it's an after market conversion, it can't be put back on your car" (quote from Merc dealer) BE WARNED.
3 months later, the thing has started to use oil at a rate of 200 miles per litre, due to the fact it was run with no oil in the engine; this was something I did not contribute to.
For those of you who don't know, it's recommended you check the oil weekly on these cars as they DO BURN oil at a rate of 0.6ltr every 1000km; running them low on oil will get you "turbo death" in the end, so check the oil regularly.
These cars also suffer from the oil scrapper rings, which are located underneath the piston ring; they are supposed to prevent oil entering the combustion chamber, but after a while get "gummed up" and don't work as they should, allowing oil to mix with the fuel, and the car burns the mixture. It should be noted here that oil burns hotter than petrol, so if your car is burning oil/petrol mixture, you can start to kiss goodbye to your valves, as they will start to burn out.
A good recommendation here, is if you wish to purchase a smart, buy one with the least miles on that you can, preferably a 1000 miles and no visits to an official network dealer; that way it's up to you where you get it serviced.