Hopefully not a useless bump but this thread was linked from a new thread about MyKey.

I got an Avis Ford in the fall with the MyKey but fortunately both keys were on the fused ring. One of the keys was programmed to limit the speed (to 66 mph, unwelcome on the roads I was going to be on that had 70 mph limits!) and the radio volume limited very low...evidently some previous renter must have programmed these absurd settings. Fortunately the other key was the "master key" and through playing with the settings on the "information center" on the dash, I was able to clear all MyKeys for the vehicle, no longer having to worry about using the right key. Hopefully future renters of the same car appreciated my efforts!

They really shouldn't be renting cars out that have that feature enabled--when I rent a car, I expect to be able to use the full functionality of the car!