A quick explanation is to take the same shot with different cars. You have to make sure the angle and everything is exactly the same or as close as possible. Then you take all the pics that have each individual car in it and then go to a photo editing program and put them together with layers. Heres a more detailed explanation, multiple car tutorial.
Nice pics you have here. First few ones were kinda dark but it looks like the next few have gotten bighter I like the s2000 one. Great work and welcome to GTP .
Hey thks a lot .. you know i'm a new member so i'm so glad yo be here and share my photos with persons like you thks a lot ! (sorry for my english :$ ) new photos will come soon