Trying to figure out why green cars are cheaper:
It looks like green cars are mostly from 97 to 2003 in a roughly normal curve, while most other colors are exponential (so mostly from the last couple years instead, and dropping off dramatically once you reach 2005 and older). Not counting purple, which has 8 samples and is therefore mostly useless, hah.
Ah yes, I would seem that green cars are going out of fashion, dunno who would want a purple car =P
My theory is that there aren't many green luxury cars out there (think black!), but plenty of cheap commuter cars that are green. Another theory: younger people want green and younger people happen to spend a lot less on cars on average.
I went looking through the categories and the only time green is not the cheapest is when it's a station wagon. In that case, red is cheaper than green, but not by much.
But it's neat that greens are cheap.
also - we are building a comprehensive recommendation engine for the top 50-100 models by collecting everything from EPA & NHTSA safety data to style awards and max lifetime mileage. this is probably a month out and has required getting pretty creative about crawling a number of heterogeneous data sources