As a huge fan of Mercedes Benz i always thought i'm a rear wheel drive kind of driver, but the heavy steering of the MBZ didn't appeal to me, i wonder if All rear wheel drive cars are heavy to steer? does anyone know?!
The steering is not super light like it is on many Toyota models for example but it really depends on what you're comparing the steering feel with to say if it is light or heavy.
If you feel that it takes much more effort than it should, check the P/S fluid level and make sure the pump and all the lines are dry (not leaking).