Road noise can be very specific, depending on the surface you are driving on, it is also very much affected by the type of tyres you have. As previously noted, things like the air running over wing mirrors etc can also make a difference. If it's mainly road noise, then go and find a newly laid road surface and drive at the same speed, see what you hear then. Sometimes I feel mine is no quieter than my old mini, but other roads it's almost silent. I'm running 20" rims with continentals fitted.