Well I got one done. I hope it makes since. This is the first time I did one with pics!! Plus I didnt preupload them, so I just added them as attachments. I will try and explain each pic as they are in order.
Now Pic 1
As you can see I chose the 350Z side view. To make it as easy to start with. Plus you can see I already made a layer copy of the car I outlined. When you have the car outlined with the poly lasso. You need to make sure you go to select/ and inverce then you hold down the shift key then start deslecting the things you dont want to paint (as you can see that is what I did) Once that is done make sure you go back to select/ inverce again. Then make a layer copy of it. I always make a duplicate of the layer copy (incase I mess the first one up). I also turned off the background layer so you can see more clearly what is being done.
Pic 2
Now you need to go to image/adjustments/desaturate That will turn you car gray! (when changing the color of the car it is always best to make it gray first)
Pic 3
Now you should have a gray Z. Now got to the layer pallette and at the bottom of it click on the blending options icon. (as you can see I have it circled in read) then click on gradient overlay.
Pic 4
Now the layer style window will open. You need to change the blending mode to overlay: then go to angle and change it to 35% as shown. Next change the scale to 10. Now you have a car that is black in the front and white in the back.
you have to wait for the rest as I have to submit this one and make another post to get the last two pics.