The following packs have the corresponding extras:

American Muscle Car Pack
1965 Pontiac GTO
1968 Pontiac Firebird
1970 Buick GSX
1970 Dodge Coronet Super Bee
1966 Chevrolet Nova SS
1969 Shelby GT500 428CJ
1971 Plymouth GTX 426 Hemi
1967 Dodge Coronet W023
1968 Dodge Dart Hemi Super Stock
1964 Ford Fairlane Thunderbolt

Launch Bonus Car Pack
1965 Ford Mustang GT Coupe
1997 Lexus SC300
2011 Tesla Roadster Sport
2011 Ruf RGT-8
2011 Koenigsegg Agera

Limited Collector's Edition Pack
1965 Ford Mustang GT Coupe
1965 Pontiac GTO
1968 Pontiac Firebird
1970 Buick GSX
1970 Dodge Coronet Super Bee
1966 Chevrolet Nova SS
1997 Lexus SC300
1969 Shelby GT500 428CJ
1971 Plymouth GTX 426 Hemi
1967 Dodge Coronet W023
1968 Dodge Dart Hemi Super Stock
1964 Ford Fairlane Thunderbolt
1981 BMW M1 Design Challenge
2008 BMW Z4 M Coupe Design Challenge
2011 Tesla Roadster Sport
2008 BMW M3 Design Challenge
2010 BMW M6 Coupe Design Challenge
2012 BMW M5 Design Challenge
2011 Ruf RGT-8
2011 Lamborghini Gallardo LP570-4 Superleggera
2010 Noble M600
2011 Ferrari 458 Challenge
2011 Koenigsegge Agera
2011 Ruf Rt 12 R
2011 Bugatti Veyron Super Sport

Track Packs
Test Track Benchmark with 16 Layouts
Top Gear with 20 Layouts