Why is it when I engage my car is either drive or reverse I have to give it some gas to take off? Shouldn't it start automatically moving foward or back without any gas at all? That's what my other Mercedes cars do so is that any sign of a problem?

Also, when driving I can sometimes see the RPM guage "ticking" instead of going up smoothly..

Other then that the car drives great, no slipping and pulls very strong..