If you start finding it tricky to turn the key in the lock (check the steering lock first!
) or to remove it, your ignition lock may be going bad.
I don't think it's actually at all common, but some members have had night mare scenarios of keys stuck in locks, not being able to go anywhere, etc. etc. which could have been avoided if they'd noticed the problem earlier.
Also, as the Mercedes locks are made of some outrageous strength metal (you'd expect nothing less) most people can't even make a scratch if they have to try and drill them out.
Same deal with Mercedes locking wheel nuts... won't drill off for the world