As I am right handed, I use a Hume JIT crossdraw.
In order to use the gun with any degree of success, practice is needed. Best to roll window down
, wear a headset, and wraparound safety glasses.
Lots of dry fire first.
Remember, the firearm is a last resort in this situation, learn proper techniques to lesson the chance of needing a gun in the car.
I leave 15 feet mini mun between me and the vehicle in front of me at any stop light/sign. Do my best not to be boxed in any lane. Always courteous.