Four sketches of mine...

Im sorry about the quality, but they were taken from a camera... :banghead:

But anyway, let me know what you think...

http://i49.photobucket.com/albums/f265/slam_sted/P1010089.jpg

This is what I think is the best...
http://i49.photobucket.com/albums/f265/slam_sted/P1010090.jpg

http://i49.photobucket.com/albums/f265/slam_sted/P1010091.jpg

http://i49.photobucket.com/albums/f265/slam_sted/P1010092.jpg

Your designs are all quite complex. Maybe you try to simplify them a bit first so that you can handle the shapes better.
Try to add some dark shades to the wheels and add some real tires, trust me it will look much better. Many tend to leave the tires away or make them super, super flat, but the rim's presence can only work when a tire is wrapped around it.

I like the first one most. The perspectives you have chosen are quite difficult, but you handled them well.

Keep it up! I'd really like to see more of this.

brave angles. nice.

watch for car's body being too narrow.

OK, thanks for the tips... I'll start on some tyres next to get the hang of it... again, thanks... :wink: