What IS a postal code? Is not a postal zip code; so what is it?

I suppose it depends on what country you are in and which CG's website you are using. In the US use the zip code.

if your on the webpage, in the upper right of the screen is a flag, pick which country you are in to get the right site.

Sadly one cannot access Cargurus if you try to input Canadian Postal codes which have 6spaces unlike US zip codes with 5 spaces.Wake up Cargurus to the Can;reality!!!Ashley