Hm, I like that. Very good advice.I would add maybe a third car to the left and make the two cars in the background blurred, just like you have the one on the right in the photo. Then play with some angles.
I would also play with lighting and make the blue car stand out more.
You even pointed out the lighting. I've been trying to figure out some lighting setup that works. That's actually why it has the black background. I wanted to go with a green to play with, but I couldn't figure out a lighting setup that worked to show the color correctly.