Let me start with this 1, since it close as it gets to 5th gen related.
A proof of concept model.
Basically you take a 3rd gen Roc Z, sit in the back seat, then pull the front back till you can reach comfy, then weld. A real roadster, no doors or top, if it rains, drive faster.
Now it could use some refinment but was fun giving it a go in plastic.
many more pics
http://thirdgenchat.org/z28ster/