The new Forza Motorsport 3 downloadable content pack for May is the Exotic Car Pack. Featuring 10 boutique manufacturers including Mosler, Spyker, Gumpert, and Devon.

Included is the SSC Ultimate Aero which pips the Bugatti Veyron with a top speed of 256mph (un-tuned).

More info on all the cars featured in the game, including a downloadable CSV of all the data, can be found on my Forza 3 page available here.