You must purchase all of the following cars, and have them all at the same time. They do not need to be in the same garage, and you will be given another garage when you run out of room. A total of 2,003,000 Credits is required, and all cars are available from the start.
Lamborghini Murcielago R-GT - 650,000CR
Lamborghini Diablo GT - 315,000CR
Lamborghini Diablo VT 6.0 SE - 293,000CR
Lamborghini Murcielago 6.2 - 273,000CR
Lamborghini Gallardo - 177,000CR
Lamborghini Miura P400 SV - 150,000CR
Lamborghini Countach 25th Anniversary (QV) - 145,000CR