not knockin' the green, cuz I like green and it looks good in the rendering, but...
oddly enough IMO the red looks great with the overall shape/features on the car to me... and keep in mind I don't typically like red cars so that is saying something. There is just something to the shape that makes the green look slightly "bloated" whereas the red somehow tones it down (why doesn't that work with dresses?? Gotta be a skinny chick if she is wearing red...)
first glance, gut shot the red really caught my eye, so without over-analyzing it I would consider red.
All four look great to me actually (blue my least favorite) so I can see why you are having a hard choice. Isn't it great to have some a-hole like me come in and throw a monkey wrench into your already noted, "...that made the decision to go green even harder"
The copper color looks good too, but WAY too many cars are being painted copper lately - it is almost dare to be different to stay with a color like red, green, orange these days hahaha. (i.e. Bad Penny looks awesome and I saw it at SEMA, but last year there were at least 15 other copper colored cars at that show)