the 'perfect system' ?
gee... i'll have to think a bit on this one

one system i know of does have wireless incorporated into it's function so when impacts happen it notifies management at the time of impact with all the required information such as operator ID, impact time, force, speed etc.
I know of one company that has these and it has made a large difference in thier accident/damage ratio since they were installed.
This system is on a shockwatch model that uses the standard green 'programmable' key access.

I suppose though if any improvements could be made on anything a more secure access system would be one that could utilize the wireless system with a sensor that could sense a transmitter built into the operators key or some other device that when he got on the truck it would pick that up and identify him as the operator without his direct intervention and log him into the truck, and when he exited the truck at signal loss it would log him off.
I know this type of access would have its own set of problems if more than one access signal was detected in the vicinity of the system but the concept is sound. I'm sure it wouldn't be too hard to get that sorted out to set it up to allow only one access at a time. Maybe devise a method to have a 2 part access, detect the signal and then require the operator to verify it by entering an access verification code via his key or manually on a keypad.

Frankly i'm not sure of any good way to improve the wireless system but thats just a thought that came to mind.

You'll have to give me a few to think some on this.