They are almost identical to the w124, so no electrics to go wrond there. But don't excpect too much of a speed boost from a similarly powered w124. They are smaller, something like 200kg lighter than the w124, comfy for 2 people, but the back seats don't have too much room.

I've had my 201 2.5turbo for an year already and the things I changed are: leaking A/C compressor, one belt tensioner (don't know if it's called like that, the one that looks like a small shock), and a water pump.

The best mileage I've got is 36mpg on a long trip (twisty) and 31.3mpg on the highway (was going fast though, min speed ~80mph and max 125mph, I think the avarage was around 95mph)

With mixed driving city/highway I get around 27.7mpg (more highway than city, but my city's traffic is crazzy)

A friend of mine has a 2l 201 and he says it consumes close to 47mpg on a long trip.