Interesting idea, I see you also recognize that there is more than one way to make a car shorter (instead of slamming it, you can squish it too). The front looks a little empty though, I suggest making the grill run another row or so down into it so that it doesn't look so empty. Also, shrink the wheels and the wheel wells, they look to huge for the height of the car. Aside from that it's all stuff I would do with the car that I'm just going to point out to you; like how boxy the back of the cocpit is, and other design issues. In reality, the 300C really doesn't have alot to pull from, because in short it's an ugly car. It's pretty fast to see in a test-drive, but that still doesn't make up for the ugliness of the car. I'm going to stop rambling now...