This is mainly for you to role-play however you want it as,
Let's say two people owns infernus's. Me and you. I own the infernus, and I do a descriptive /do of what my infernus being role-played as, let's say a NSX. Then you own an infernus, and you do a descriptive /do stating that your infernus would be role-played as a Lamborghini. So, you should always stay IC and not call it an 'infernus' and use their IC models. Such as for example.
eg: Kazuo Takehiko exits the NSX, as he peers over at the Lamborghini in-front of him Kazuo Takehiko looks over at the owner, as he would look shocked - Slowly walking towards him, shifting his gaze at the laborghini
Kazuo Takehiko says: Sweet lamborghini you got here, how much was it?
(Lamborghini owner would be John) John would look over at Kazuo exitting the NSX and walking towards him
John says: Thanks man, what a nice NSX you've got there as well.
There you go, that's how you keep the two Infernus's IC. Just because it is an infernus and you have the same car. It doesn't mean both are the same vehicles, since you both have them role-playing the two models differently.