Doug R. wrote: First, I think if we can implement lockable containers, we should do this.
Second, that means gas tanks can be locked like any other container - you could just make the key for them the same as the key on the car for simplicity's sake. Of course, this gets complicated when someone breaks off the car lock - you then need two keys when you put a new lock on. So, really, this would only work for the key that was in use at the time the engine was built, but it's still better than nothing.
On your second point, can't we make it as simple as this? :
If car is locked, gas tank is unaccessable.
Car unlocked, gas tank accessable.
That saves multiple keys...