Addressing Similar Content: When to Canonicalize, Noindex, or Do Nothing by @@joshuacmccoy
A great example of this is an automotive sales site which features pages for car makes, associated models, and variations of those models (2Dr, 4Dr, V8, V6, deluxe edition, etc.). The initial thought with this site is that all of the variations are simply near duplications of the model pages. So why would we want to annoy search engines with this near duplicative content when we can canonicalize these pages to point to the model page as the representative page? We moved in this direction but still the anxiety on whether these pages could succeed made us move to canonical to each respective page.