It seems to be highly car dependant.
But imo before you make any drastic changes maybe it would be good idea to wait what Dany's friend thinks about overall bumpiness. After all realism should be number one priority, of course some artistic liberties can be taken where appropriate.
Have you made back to back testing with Ascari and Vallelunga? To me Vallelunga is much smoother than current Ascari, point being that some tracks just are smooth for real and there's not much happening in the wheel.
I believe one point of this high res phys mesh thingy is that bumps, if there are any, aren't low res sharp polygons because AC's physics is so sophisticated (sorry, probably some of those fancy words I used are wrong but I hope you know what I mean). So tracks doesn't necessarily need to be bumpy, but if they are all bumps will be detailed as they should.