If you want two sure ways of getting an Infernus on GTA IV and being able to stash them on the safehouse parking space:
1) In GTA 4, Niko will be given an Infernus as a present, so he doesn't have to make much of an effort to get one! After he has helped his friend Bernie (Florian) through the relevant missions, Bernie will ring and tell him that he has left him the gift of a car, which was originally a present from Bryce Dawkins, Bernie's boyfriend. When Niko goes to the "B" marker on the map in Algonquin, he finds the Infernus.
The Infernus is a difficult car to find on the streets of Liberty City, but occasionally you seem them parked up. But of course when you drive Niko around in his own Infernus, you will see them spawned in traffic here and there.
If you keep the Infernus gift on a safehouse parking spot, at least Niko can use it when he wants, and repair it if he needs to.
2) In one of Stevie's requests to find a vehicle, there is a gold Infernus. When Niko finds it, don't take it to Stevie's garage, but take it to a safehouse parking space, stash and save. The gold Infernus Stevie wants will respawn and Niko can go and get it again and take it to Stevie's garage.
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