i was always wondering where i could find an infernus in campaign when i beat all the missions for bernie i got the infernus he gives u but i want to kno if there is any sitting around on campaign i can get

I don't think there are any more.

Look for car dealerships .-.

I don't think there are any dealerships that sell an Infernus.

Aspect is right. They aren't in the dealerships. You can find them, though there are one of the more rare cars in the game. Look around central Aldernay near all the stores and shops. Try driving a nice supercar, like a Comet or Super GT. I found one while driving a sportscar between Brucie's races, oddly enough. You might want to try replaying some of Brucie's Aldernay races and driving around the area I described above with a nice car. You will eventually find an Infernus, but it can get a little annoying looking for a while and coming up empty.

You'll actually get one from a guy who does missions in the future. But that happens on the back 9 of the game.

He may be past that point. You get one from Bernie after his last mission. He will send you to an alleyway on the west side of Algonquin, where you will have a beautiful, brand-spamking-new Infernus waiting for you.