When I was very small, I dreamed about mounting a bazooka in one of our trucks (my parents ran a trucking company). 55 years later...
Having charged twice in Atlanta - I think you're going to need a higher firing rate than 4 rounds per minute.
Just for comparison a US Navy WW II vintage 5 inch naval gun (main armament on destroyers and secondary armament on everything larger) has a muzzle energy of 7.8 MJ. The main gun on the Abrams tank firing an armor piercing round is 11.1 MJ of energy. The high explosive round (which also has anti-tank capabilities) has a muzzle energy of 7.0 MJ. A rail gun capable of these characteristics would have a muzzle energy of 8.5 MJ. So your hitting power would be somewhere in the range of a modern tank and line up a few Model 3s and your hitting power would be a bit better than a WW II destroyer broadside. Firing each round would take 2.6 KWh of battery energy. Your moment of geek...
Oh good. So we don't use it to get the Atlanta driver's attention; we use it to remove them from the road. I wanted to call my Tesla "Gort" after the robot in The Day The Earth Stood Still because the nose cone reminded me of Gort's visor. But I figured that would be wrong because I didn't have an actual death ray behind the nose cone. So I changed it to Klaatu, the spaceman in the movie. After I get one of these installed, I'm going to change the name back.