The “Lamborghini” in Vice City is modeled by the “Infernus”.

Here are ways to get it:

Grand Theft Auto: Vice City

Parked in front of the mansion owned by Ricardo Diaz, and later Tommy Vercetti. Prior to the mansion's change of hand the Infernus is randomly colored, and thereafter the car appears with a unique white body color.
Parked inside North Point Mall, at the north side. However, the player cannot drive it out.
Spawns in the car park next to the North Point Mall.
Found driven throughout the city,