my first page of sketches
comment
anyone can tell me what i need to be a cars designer

you draw your cars too cartoonish and i think it is because your wheels are too small....but keep sketching,sketching,sketching!!!

neat lines, good identification of elements, color shadings aren't bad, composition of ideas is okay too.
You need to learn basic perspective. In cars its a little bit more complex, so tracing over (and over) different set of images in perspective is a good way to train your eye to see how they should look naturally.