I don't know if this ad is going to have the intended effect.

Those kids made me laugh so hard.

Bro, this ad is funny-as, but I don't see how it relates to its apparent message.

Aside from the seriousness they were trying to accomplish from this, these kids need a show.

The kid in the back seat is the next Boomhauer.

I have a simple test for this one. If you can no longer judge what is an appropriate amount of time to maintain eye contact with people, your too high to drive! (anyone who smokes should know what I mean)

Up until that point however I honestly believe it can slightly enhance ones standard of (safe) driving, especially if one is prone to a quick temper or impatience/ "a need for speed". Frankly some people are more of a liability when completely sober! (I know I used to be till I made myself calm down)

Unlike alcohol Pot tends to make one objective about how impaired ones senses have become. If your too high the little voice in your head tends to think "I'm really high, maybe I shouldn't drive yet?" rather than "I'm not pissed, I'm amazing. We can totally pull this off!".

Pot can also be surprisingly self regulating too, your most comfortable road speed is pretty much inversely proportional to how high you are, unlike certain other fermented vegetable products which are known to have the opposite effect....

IMHO existing laws for driving without due care and attention etc. are perfectly adequate to deal with potential abuse. I'm not saying it can't be a problem but equating it with drink driving is foolish and necessary to me.
This advert seems to have hit on a nice way of approaching the subject by simply suggesting you think twice about driving when baked our of your tree, rather than some unrealistic draconian shock tactics (Like the us advert at the drive through).

Good work NZ! (Wish I could afford to live there, seems like an awesome place)