[AAABEST]

So smoking pot in a car is okay but drinking a beer in a car is bad?

Actually in a strange way yes. Driving drunk can cause you to crash your car killing someone in the process. Driving stoned won't cause you to crash your car. You may get lost or something, but you probably won't crash.

[Mr. Mojo]

Yep, if anything, driving while stoned causes one to drive more slowly and carefully (although that could partly be attributed to super-awareness/paranoia about cops). And unlike alcohol, pot doesn't affect depth perception.

[weegee]

NORML's own position prohibits driving under the influence of marijuana:

Policy debates regarding marijuana-law reform invariably raise the issue of marijuana and driving. This is a valid concern. In fact, NORML's own "Principles of Responsible Cannabis Use" invoke a "no driving" clause, stating: "Although cannabis is said by most experts to be safer than alcohol and many prescription drugs with motorists, responsible cannabis consumers never operate motor vehicles in an impaired condition."