people can't even drive in straight lines let alone 3 dimensions...
here's a ferrari wagon...
doesn't look all that different does it?
as far as curvy and aerodynamic... they were doing that in the late 80s and 90s.... the trend now is more angles and boxes, more like it was in the 70s to 80s
I forgot which car designer it was.. but he said,"Do not be a slave to the drag co-efficient." Reason being is that cars will then all tend to be the same flat shape and without any style.