Dr. Ak that is some huge improvement. You are showing value (shades) that is good. I would watch out for the harsh pencil lines around the head/turn signal lights and intake ducts in the bumper. Basically you want to allow your value differences to form the lines for you.
If you are interested check out this book from the library and if you like go ahead and buy it.
It is not focused on cars but on drawing.
http://www.jdhillberry.com/
http://www.jdhillberry.com/book.htm
The peops at amazon all gave it 5 stars. Probably the authors family memebers...
just joking. I have the book too.
Also look through your library for books on grid techniques, and of course the mother of all drawing books.
The new drawing on the rights side of the brain.
By Dr. Betty Edwards.
al