These cars (Porsche and Ferrari) are so common these days that I can't see the point of waiving. Downtown Chicago Ferrari's are as common as Camry's in the 'burbs. I counted 5 outside of the two nouveau riche steakhouses this evening, another 5 Porsche's, and 8 MB SL's. You'd be waiving like the Queen on Coronation Day if you waived at every Ferrari and Porsche you saw in Chicago.

Better answer is waive at people with PCA stickers, or better still take your car to the track and race them.