Premium unleaded or just regular unleaded for my 1994 C180 Euro??? It seems to run better on regular, the car is not so noisy and the idle rpm is lower like 650 instead of 850 to 900 on premium. I may be wrong though. There are less vibrations on the steering wheel and in the car with regular. The manual says you have to remove a resistor under the wiper water reservoir, is this necessary? If I don't what happens? Regular is cheaper all the time and if there are no bad reactions with it, I will continue to use it although the manual says you can only use it for emergencies. I have noticed that Jap and Korean cars mostly use regular if they are 4 cyls and up to say 2.6ltr, so why does the Benz need premium???