Hasta La Motion!

Hi im making a few tests of fast moving car along a road and can get most motion blur techniques to blur everything acceptably apart from the wheels. The techniques I have tried so far are Mentalray No deformation, mr full deformation, mip_motionblur. Mentalray full deformation gives best results on wheels but takes way to long and for the amount of frames I want to render and it tens to flatten the reflection properties of the material to much.
How do you guys go about achieving photoreal motion blur for this type of shot without it looking nasty?