You can carry your gun in your car legally without a permit... just gotta be careful as to where you have it. And seeing as how your 18, I'm assuming your talking about a rifle and not a pistol... since you legally can't own one until 21. But from what I've heard, it's legal to drive with a firearm as long as it isn't "hidden"... like laying on the passanger seat is legal... but I could definatly be wrong, just what I've heard.