Say there are three levels of security system (this is not true, just an example). They are Basic, Mid and Hard. And there are one or two tasks in stealing a vehicle, break-in and hotwire. If this where the case it would just take a few items to be added to the game. The items don't have to do anything but have a description, have dimension and weight, and have value. Nothing fancy.
For break-in there could be something like the Blandford Break-in Kit (5000c), the Midtronic Break-In Kit (10000c) and the Helios Break-In Kit (15000c). Hotwiring could have something like the Blankline Hotwire Kit (5000c), Metrogone Hotwire Kit (10000c) and the Heavyspark Hotwire Kit (15000c). Only sold at shady places.
If you want to steal a car with a Mid Security System you need to use your one time purchase item and a Midtronic Break-In Kit (or better) to open the doors. Then you need to use your one time purchase item and a Metrogone Hotwire Kit (or better) to get it started. Then go. The kits are used up by the attempt - succeed or fail. If your Kit's not good enough for the job, it's used up and you fail.
Motorcycles would be cheaper to steal than cars and I think that's a good thing. All the skill checks can be left alone. It just goes from, "Did you roll high enough?" to "Do you have a good enough kit and did you roll high enough?". It also means that you no longer have Bob sitting at a car trying the commands 27 times until they get lucky. Unless they want to fork over a LOT of chyen that is.
The exact costs would need to be determined by people who knew the average value of cars better. But the goal here for me would to force a car thief to be more discerning about what they even try to steel. It would also allow players to better protect their vehicles as making the cost of theft prohibitive is a valid tactic. It might also push car thieves to focus on more high end targets if they really want the best cost to reward ratios and not just steal every single thing they see sitting about.