I've had a '72 Datsun 240 Z, a dog '80 Corvette, an '02 LS Miata, and '06 NC and now an '04 Z4 3.0. My Z4 is the quietest top up of the convertibles. I took off the new run flats that came on it and the ride and quiet was tremendously improved. The Z-4 have the horrible "sticky steering". I have since rectified that problem by doing the grease zerk fix.
It was so bad I was ready to get rid of it and find another NB. Now that the steering is repaired, I really appreciate the Z4. The Z4 felt heavy at first (which it is) but now it corners just as well as the Miata's. It's well balanced near the 50/50 weight distribution. I just throw it into the corners and it tracks like on rails. The build quality is superior in the Beemer, which it should be due to the higher original price.
The Z4 has other many plusses, but I will always love the little NB,
my 1st true roadster.