If you snatched up a used copy of Turn 10 Studios' two-million selling racer, Forza 3, you now have the chance to tune up the game with some new content from Xbox Live. There are four new packs available for purchase, each previously only available through new standard and limited editions of the game. Here's a rundown of each pack's specs:

• Sidewinder Proving Grounds Track Pack (400 / $5) -- This pack features 18 courses, including an updated version of the Sidewinder Proving Grounds from Forza Motorsport 2.
• Benchmark High Speed Ring Track Pack (400 / $5) -- A four-mile stretch of road to test your car's mettle, the Benchmark High Speed Ring Track Pack also features a large parking lot environment for online multiplayer games of "Tag" and "Keep It Clean."
• Motorsports Legends Car Pack (400 / $5) -- As suggested by the name, this pack features 10 of racing's most classic cars: 1965 Alfa Romeo Giulia Sprint GTA Stradale, 1964 Aston Martin DB5 Vantage, 1981 BMW Motorsport M1, 1960 Chevrolet Corvette, 1969 Dodge Charger Daytona Hemi, 1957 Ferrari 250 Testa Rossa, 1980 Fiat 131 Abarth, 1967 Lamborghini Miura P400, 1971 Nissan Skyline 2000GT-R, and the 1965 Shelby Cobra Daytona Coupe.
• VIP Membership Car Pack (800 / $10) -- This pack unlocks VIP status for your profile in Forza 3, giving you special recognition as a VIP on leaderboards, in multiplayer lobbies, on ForzaMotorsport.net, in the in-game storefront and places your auctions at the top of the Forza 3 auction house. It also unlocks five additional cards: 2008 Aston Martin DBS, 2009 Chevrolet Corvette ZR1, 2007 Ferrari F430 Scuderia, 2007 Lamborghini Gallardo Superleggera, and the 2007 Porsche 911 GT3 RS (997).

During the month of March, Turn 10 Studios will donate $10 for each download of the VIP Membership Car Pack (up to $100,000) to Save the Children. The proceeds will be donated to victims of the Haiti earthquakes.