ProStreet Extender Pack On 360 Today

The booster pack should finally come to the 360 version of the game today at 10am PST in all territories.
All the cars will be available to purchase in the garage.

There will also be two packs available a few hours later for 480 points each, that will give you the cars for free:
#1: Dodge Challenger Concept, Lancia Delta Integrale Evo, Porsche 911 GT3 RS, Lamborghini Gallardo Superleggera, Porsche Carrera GT, Aston Martin DBR9
#2: Honda S2000, Porsche 911 GT3, Audi R8, Aston Martin DB9, Mercedes-Benz SL65 AMG, Koeniggsigg CCX

Edit: the update is now available, start up the game and download the 500MB update.

Only two cars are available free: the Seat Leon and the '69 Pontiac Road Runner. All other cars are only available through Microsoft Points and cost 200 points each.