Dude, my friends and I smoke in the car all the time. Every time we go someplace, there's at least one bowl being passed- driver hits too. I'm not necessarily advocating driving stoned, but the driver often takes a hit right in front of the windshield, no worries. MOST of the time, cops won't pull you over for that, cause you can ditch it (or they don't see it).

Either way, it's safest to not smoke and drive, the guy was right. But he's still a fucking douchebag.