I have a 2004 203 wagon. It's a very decent little car. Be aware it is quite a bit smaller than the 124 wagon, the carrying capacity is much less. It's much more biased toward good handling than ride, so expect less of a luxury car feel.

The M112 V6 does not have either the wiring harness or head gasket problems, those were with the M104 I6. MAFs don't last forever, but are not that expensive nor difficult to replace. Really, there aren't many problems with this drivetrain.

I can only think of a few problem areas with the w203. Check the climate control to be sure air flow can be directed to the defrost, dash, and floor - use the knob on the right of the climate panel. The front suspension bushings are not noted for long life, so make sure the car tracks properly, does not vibrate at highway speeds, and does not make rude noises over choppy pavement.