Forza Motorsport 2

The following cars are required for the achievement:

2003 Porshe Boxter S [36,000cr]
1989 Porsche 944 Turbo [30,500cr - Level 6]
2006 Porsche Cayman S [43,500cr - Level 6]
1970 Porsche 914/6 [44,500cr - Proving Grounds - European Open]
1982 Porsche 911 Turbo 3.3 [61,000cr - Level 15 in Europe]
1973 Porsche 911 Carrera RS [79,500cr - Amateur Cup Races: Sports Car Classic]
2007 Porsche 911 Turbo (977) [135,000cr - Level 19]
2004 Porsche 911 GT3 (966) [140,000 - Level 19]
2007 Porsche 911 GT3 (997) [163,000 - Level 19]
1987 Porsche 959 [187,500cr - Level 25 in Europe]
1995 Porsche 911 Gt2 [203,500cr - Level 34]
2003 Porsche Carrera GT [250,000 - Level 34]
2002 Porsche #57 Larbre McDonalds 996 GT3 Cup [375,000cr - Level 37]
2003 Porsche #22 3R-Racing 911 GT3 Cup [275,000cr - Level 37]
2005 Porsche #55 Applied Materials 911 GT3 Cup [ 275,000cr - Factory-Spec Races; Porsche 914/6 Challenge]
2005 Porsche #66 AXA Racing 911 GT3 Cup [275,000cr - Level 37]
2006 Porsche #81 Synergy Racing 911 Gt3 Cup [275,000 - level 37]
2005 Porsche #3 lechner Racing School Team I 911 GT3 Cup [275,000cr - Level 35 in Europe]
2006 Porsche #82 Red Bull 911 GT3 Cup [275,000cr - Manufacturer Club Races: Porsche Sports Car Club]
2004 Porsche #23 Alex Job Racing 911 GT3-RSR [300,000cr - Level 37]
2005 Porsche #31 Peterson-White Lightning 911 Gt3-RSR [300,000cr - Level 37]
2005 Porsche #44 Flying Lizard 911 GT3-RSR [300,000cr - Level 37]
2005 Porsche #5 XBOX 360 911 GT3-RSR [300,000cr - Rivalry Face-offs: Battle for Europe]
1998 Porsche #26 Porsche AG 911 GTI-91 [325,000cr - Factory-Spec Races: Porsche 911 GT2 Challenge]
1987 Porsche #17 Racing Porsche AG 962c [350,000cr - Endurance Races: Porsche Grand Prix of Nurburgring]
2004 Audi TT Coupe 3.2 Quattro [11,000cr]
2000 Audi S4 [24,000cr - Level 9]
2004 Audi S4 [35,000cr - Level 9]
2003 Audi RS 6 [86,000cr - Level 9]
2006 Audi RS 4 [94,500cr - Level 9]
2000 Audi AWE Tuning SilverBullet S4 [214,500cr - Manufacturer Club Races: Quattro Club]
2002 Audi #1 Champion S4 Competition [275,000cr - Level 31]
2003 Audi #1 Champion RS 6 [275,000cr - Level 31]
2004 Audi #8 Audi ABT TT-R [300,000cr - Professional Series: Class C World Trophy]
2004 Audi #88 Audi Sport UK Team Veloqx R8 [350,000cr - Level 49]
2006 Audi #2 FSI Champion Racing R8 [350,000cr - Semi-Pro:K&N Filters 700HP Invitational]
2001 Audi $4 Johansson Motorsport R8 [350,000cr - Professional Series: Legends World Trophy]
2002 Audi #1 Infineon Audi R8 [350,000cr - Level 50 in Europe]
2004 Audi #5 Audi Sport Japan Team Goh R8 [350,000cr - Level 49]
1992 Volkswagen Golf GTi I 6v Mk2 [9,000cr]
2004 Volkswagen Beetle [10,000cr]
1995 Volkswagen Corrado VR6 [10,000cr]
2003 Volkswagen Bora VR6 [10,500cr]
2006 Volkswagen Golf GTi [11,000cr]
2003 Volkswagen Golf R32 [16,500cr - Manufacturer Club Races: Volkswagen Driver's Club]
2005 BMW Motorsport M3 E46 Coupe [38,500cr]
1997 BMW Motorsport M3 E36 [31,000cr - Level 17]
2002 BMW Motorsport M3-GTR [175,000cr - Level 17]
2005 BMW Motorsport #2 BMW Motorsport M3-GTR [300,000cr - Level 40 in Europe]
1999 BMW Motorsport #15 BMW Motorsport V12 LMR [350,000cr - Professional Series - R1 World Trophy]
2004 Mercedes C32 AMG [48,500cr]
2003 Mercedes CLK55 AMG Coupe [52,500cr]
1954 Mercedes 300SL Gullwing Coupe [59,500cr]
2005 Mercedes SLR [220,500cr - Level 41]
1998 Mercedes AMG Mercedes CLK GTR [250,000cr - Level 41]
2004 Opel Speedster Turbo [34,500cr]
2003 Opel #5 OPC TEAM PHOENIX Astra V8 [300,000cr - Regional Championships: Deutsh C-Class Championship]
2003 MINI Cooper S [9,500cr]

Patience in the Auction House will often net you prices that are lower than those listed at the dealership. If you haven't unlocked a car, the only way to get it, is through the dealership.