That sounds bad
perhaps the oil leaks arent that serious and that the 4th cylinder is just something simple like no spark, bad wire, or rotor or something. Dont give up on it yet, its a Benz!
2000 C230 Kompressor
1988 190e 2.3 - 225K miles, owned for 7 years. I cannot say enough good things about this car. Very well built, even at 225 it ran like new.