I've been drawing since I was little, but I started on the car art about3-4yrs ago. I've got about 4 art pads filled up with various art. I've basically been drawing cars that I like or think look cool. I also like to draw things that interest me or I see somewhere and think look cool. So I have some pictures I drew that I saw on a comic cover or a movie poster (ex. the Cadillacs and Dinosaurs pic/ Mad Max pic). I'm also doing concept art for an Indie game developer. We're currently working on our first game.
I normally just use a pencil to draw out everything and then go back over it with pen to make it stand out more. It also prevents the art from fading. I then use color pencils for coloring it in. It fades a bit, but it's the best thing I could find to color the pictures in with.