Curvy or straight cars need different treatments. I say stay close to the factory look, and right for the period, maybe a bit thicker striping but same proportions.
Same goes for wheels. A set of globes look tough on anything up to XF but put them on an FG and it's wrong-town.
After all, the people that designed them are professionals.
The eye likes to see things in 1/3rds, just like in photography and painting. So break up the car into sections and apply the "third rule" and you're off to a good start.
