Find a Testarossa sitting somewhere, press X to steal.
Police will be alerted, but just hide for 5 minutes or so. After that, the car is yours. Drive right by and they will do nothing. Then get in a street race at a stoplight by burning out. Don't crash tho...
Win the street race, then drive downtown for some ice cream. Wait, something's not right...Uhh oh!
Gonna have to buy some missile launchers that will insta-attach to your Ferrari with fake money and defend yourself, but you car's armor points are way to low. Both you and your supermodel tag-along girlfriend die in a glorious fireball. Not a problem since you can respawn, but you didn't save any of your progress, so you'll have to steal the Ferrari all over again. Bummer.