Don't know if is possible, but considering that you can use trains, isn't possible that you have a setting that allow you to use any vehicle, for example to use a car for it's speed.
Sure that don't really make to much sense, is more to be able to travel faster.
It could start disabled by default.
Ah yes, good point :) Of course I could whitelist mod vehicles on a case-by-case basis (and I likely will do that as well) but it is easier just to optionally allow players to enter any of them.
