lol no it's not
I drive standing up on country roads. It's an amazing feeling.
Everyone should have the opportunity to ride or drive a convertible sometime in their life, and to stand up in it.
I would KILL to have a buggy like the one from the Gorillaz.
Um, doing something like that turns an action that is inherently dangerous (driving, albeit less so if you obey the rules of the road) into something even more dangerous. Regardless of how "careful" you may be, doing something that has the potential to put you in more bodily harm than if you performed the action normally and ran into the same trouble, well, that's dangerous. I guarantee that if you hit a large pothole, spinout, or blow a tire and wreck, you'll be in much more pain if your head is outside the car.
As far as risks go, though, it's still less dangerous than riding a motorcycle.