Pedals on all three of MB's that I've had were so stiff that the first thing I did to them was to remove coil spring about 6" long from mechanism down low on engine side of firewall. Drove 80 240D 185kmi without it; the 91 W126 has been without it for 65kmi; the 81 W123 has been without it for 12kmi. Pedals still have plenty of resistance; 'have never had a prob. with "throttle" return; they're just not so stiff that I have to work right leg so hard all the time holding the pedals where I want them. Pedal sure feels better to me not so stiff!!