Less keys on the ring could possibly help.
A word of caution if there are a lot of keys on the ring: Several years ago, my wife had her 80 240D key on same brass ring with many other keys for her office area. As she drove into the yard one day, I smelled a hot electrical something, and as she stopped, I could hear the starter running. When she reached for the key to turn the car off, she found that the weight of her keys on the key ring had kept the key in the switch from returning from "START" position to "ON & RUNNING" position - switch was held in "START" by the weight of the keys - burned out the starter.
Since then she has kept her office keys on the large brass ring and her car keys on much smaller, lighter ring with a small MB medallion. Good luck, I know how those little things can be annoying, especially when you're driving a car with no rattles, squeaks, etc., like a proper MB should be.
91 350 SDL. 81 300D