This question puts a smile on my face as I graduated from one.
In US the current leading transportation design school is CCS (College from Creative studies in Detroit MI) and I'm speaking from experience.
The other one which competes with CCS is Art Center College of Design in Pasadena, California.
In Europe without question I would go to Pforzheim University in Germany. From everything that I have seen the designs they produce are ahead of everybody.
Hopefully this helps