I am VERY HAPPY towing my 7000# GVWR Passport TT (6,950# ACTUAL, fully loaded camping weight per CAT scales) with my 2015 GMC Canyon! I've been towing that TT for 2 years now and have clocked over 14,000 trouble free towing miles. We've made very long trips (3-4 months) to New England including the mountains of Vermont, New Hampshire and New York and across the Great Plains to Glacier, Banff, and Jasper in Canada.
Expect to get about 10 mpg average while towing on interstates at 65-70 mph. My best was 11+ mpg doing 70-75 mph on a flat interstate with a good tail wind and worst was 9 mpg doing 75 mph with a very strong head wind. (I know -- I got a lead foot).
Two things to remember when towing with your Colorado: 1) ALWAYS, ALWAYS use the Tow/Haul mode and turn it on EACH time you start towing. 2) Always use cruise control when on interstates or long deserted rural highways. The truck's computer will determine the best combination of engine speed and transmission gear to give you the best towing power for your desired highway speed. Don't be shocked when the engine revs up to 6,000 RPM - that V6 is designed to handle that RPM to output towing power.
Enjoy towing with your Colorado! I LOVE my Canyon!
