I can vouch for the ride on an Aero with 18" wheels!!!
I have had a couple of courtesy 9-3 saloons which had 16" or 17" wheels on, and the ride was much better than my car......but then again, those car's weren't as fast ha ha!!!
I do miss the ride comfort of my V reg 9-5 on 16" 10 spoke alloys though
But that wasn't as fast, of course