Hey Justice, we already have a law like that on the books in New Jersey.
You can only transport firearms in a vehicle if it's unloaded, locked in a compartment that the driver has no access to within the cab (e.g., the trunk, or a locker in the back of a pickup). Furthermore, you must be on a direct course to the location you started from (home), and the place where you will be using the firearm(s). No stopping along the way is allowed. If you so much as divert your course to go get gas, or stop at a Wendy's, or whatever, and a cop pulls you over... you're screwed.
You think that stops the kids in Newark, Camden, and Trenton from carrying and transporting them all over the state and beyond?
You think that stops the mob and other criminals in New Jersey and New York from carrying and transporting theirs all over the state and beyond?