5th Gear did a sports car showdown a year or so ago and according to their criteria, a sports car had to be designed only as a convertible, seat only two, and be RWD. So while the 911 didn't cut it, the Boxster did (and won the showdown, beating the S2000, Miata, Caterham 7, and some really spooky UK thing that looked like a road legal Can-Am car...)