What I noticed is that if you come by cab, which I did a lot, and you set the marker directly onto the car, it sometimes won't show. If a car is not there, drive around a little and then go back to see if it has spawned. It usually takes around 6-10 in-game hours until you get the next text. There tend to be longer gaps between texts the more cars you have delivered. DON'T TRY TO KEEP A CAR THAT YOU LIKE!!! I did this once on my first playthrough back when I played this game on the Xbox because I thought the car would respawn, but I can assure you, IT WILL NOT. Be prepared for cops when you break into a car, especially if it has an alarm. Your payoff will depend on the constitution of the car. The garage is marked as a car on your in-game map. Once you have got the car, you have to drive it to a garage in South Bohan, close to your second safehouse. Here's a link to a map that will make it easier. You're supposed to find it with the aid of the picture.

Shortly after, Stevie will send you his first text message with a picture and the approximate location of a car that he wants you to get. After finishing the missions 'No.1' and 'Smackdown', you will get a call from Brucie and he will tell you that his friend Stevie is looking for some cars.

Gta iv real cars