So, what happens if you rent a vehicle to transport your fireworks? Does the city confiscate your Avis car? Interesting...
I'm not sure if the laws are the same everywhere, but as exampled on COPs, the LEOs in Florida only seize vehicles if you own them outright.
As viewed on COPs, the Florida LEOs spend more time seizing vehicles than they do eating donuts. But they always ask first to determine if the person they are arresting is the owner of the vehicle and if they own the vehicle outright. My guess, in Florida anyway, they can't or won't seize the vehicle if the person is making payments on it, or if they are in a rented/borrowed vehicle.
What if you come by bus or train?