Microsoft have quietly discounted a few pieces of Marketplace content related to racing games. In fact, they've done it so quietly that it is only advertised on the US dashboard, despite the fact that the discounts are applicable to other regions.
Game Add-ons
Forza Motorsport 3
• "Jalopnik Car Pack" - 400 MSP 200 MSP
Car Pack 03. Collect, race, and customize new cars. This pack contains ten cars: 2008 Mazda Furai, 2010 Jaguar #33 Jaguar RSR XKR GT, 2009 Ford #40 Robertson Racing Ford GT Mk7, 2010 Aston Martin V12 Vantage, 2010 Porsche 911 Sport Classic, 1992 Bugatti EB110 SS, 2011 BMW Motorsport Z4 sDrive35is, 2010 Audi TT RS Coupe, 2010 Aston Martin Rapide, 2010 Honda Mugen Civic Type-R 3D. In-game credits required to purchase these cars in Season Play.
http://marketplace.xbox.com/Product/Jalopnik-Car-Pack/000000...
• "Motorsport Legends Car Pack" - 400 MSP 200 MSP
Here are ten classic cars to collect, customize, and race: 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. In-game credits required to purchase these cars in Season Play mode.
http://marketplace.xbox.com/Product/Motorsport-Legends-Car-P...
XBLA Games
• OutRun Online Arcade - 800 MSP 400 MSP
SEGA's classic arcade racer returns. Experience multiplayer OutRun via Live Arcade. Race 10 Ferraris on 15 challenging courses, all in stunning Hi-Definition for the first time. OutRun Online Arcade - it's a beautiful journey.
http://marketplace.xbox.com/Product/OutRun-Online-Arcade/66a...
Avatar Clothing
• Forza Motorsport 3 Racing Wheel - 160 MSP 80 MSP
• Trials HD Trials HD Motorcycle - 400 MSP 200 MSP
• Snoopy Flying Ace Sopwith and Fokker - 240 MSP 120 MSP
The duration of the sale is unknown, so don't wait too long to snap these items up.
Just as a reminder, Outrun Online Arcade will be removed from the Marketplace in December 2011. Grab it while you can!