fro what its worth, the rf feature on my 99 E-class doesn't work at all either. the only way to operate the systems with the key is to stand within three or four feet of the car and point directly at the door. When I got the car one year ago, the range of operation was about 30 ft or so.
The car is going to the dealer on mon. for check engine/SRS light
problems, so i'll post the results of the ke issue for those who might be interested.
Steve