W202 coz I own one and for someone about my age (I'm 22) I think fuel economy ranks quite high in your car buying decision.
and the W202 is good on gas in spades. MB engines have a lot of torque right from 1000rpm and even though my car only has 148HP it feels adequately athletic and very easy to drive.
With that said, if you ended up with a cursed car you can expect these to go wrong on a W202:
- disintegrating wiring harness
- disintegrating front spring perch
- disintegrating control arm bushings
- faulty OVP
- faulty MAF
- faulty ACC
- faulty ACC display (1996+)
- faulty transmission modulator
- faulty airbag/seat buckle sensor
- faulty wiper arms
- faulty power operated seats (C230K or better)
- faulty power windows
- faulty cruise control
- faulty sunroof seal
- faulty sunroof motor
- leaking power steering
- valvetrain noise
with that said W202 has least electronics to die on you. C class is low rent but it's good in that way - it's low monthly rent to operate in terms of maintenance.
It's all really down to your luck. I had been really lucky everyone I know with a benz saw my car asked how much I got it from and everyone says I got a spankin' deal with no major issues.
I bought my car a few months ago at 210,000km, put 3000km on it thus far approaching 4000 and only the OVP has gone wrong on me. Mercedes checked up my car recently and reset the SRS light for me an all is well.
From my experience, if you want to buy old, buy the simplest one that suits your need. If the C220 came with manual windows and manual door locks I'd have picked that one.
but then if you are looking for a benz I suppose you want a grand-er version....but keep in mind the more gadgets a Merc has the more gadget is going to break.