I don't think there is a script like this yet, but it sounds fairly easy to do. One question I can think will be asked is, how will the skill be based?
It could call for the script to have seperate areas for each skill level, and the higher the level, the more chance of success. For example, at "noob" level the chances are 1/10th...while at "expert" level the chances are 7/10th.
Each locked vehicle would have a trigger near it, and when someone gets within the trigger it calls a script to first detect the skill level, then go to the proper area in the script for that skill. Then, it will pretty much just pick a random number between 1 and 10, and say the person was "noob" level, if the random number chosen was 1 it would unlock, all other numbers and it's a fail.
The part I don't know yet is the script needed to constantly monitor each person to detect their skill level, and to upgrade it as needed. I'm still new to scripting, but maybe this is a start?