3.5 I5 vs 3.7 I5?
 

I'm currently shopping around for a new(er) truck, and the Colorado\Canyon is on top of my list

anyways the 06/07 models are in my price range, and I'm wondering if there's much difference in the two engines. Power wise the difference seems negligible between the two motors ( yes i know there's 22hp more in the 3.7)

Well this is an old thread, but no one answered so I will. The 3.5 had head problems that they fixed with the 3.7. A great many people even needed to get a new head on their 3.5. I don't remember exactly what the problem is, but if you can afford to get a 3.7 you might as well. I do believe that GM will pay for the new head if you have the problem on the 3.5.

The gas mileage ratings of both models are same, but Colorado can be had both manual and auto transmission, while 3.0-L Canyon is mated only to a automatic gearbox.

Go with the 3.7 for the horse power alone. Thats another reason it came out among all the other problems.