In the U.S. EPA test, the manual is handicapped by the test procedure which dictates non-eco shift points and prohibits coasting when decelerating.
As a result, even though a manual may be rated worse than the automatic, in the real world it can return better results with just basic ecodriving techniques.
See:
http://ecomodder.com/forum/showthrea...ing-27416.html
I ran a brief test of a CVT (rated 40 mpg US combined) against a manual (rated 37 combined) Mitsubishi Mirage, and the manual won out in urban driving.
See:
http://ecomodder.com/forum/showthrea...age-27384.html
Similarly, the 2015 Nissan Micra (new to Canada) has nearly identical ratings for the manual and automatic, yet in real world ecodriving, the manual beat the automatic (4 speed slushbox) by 10%:
See:
http://ecomodder.com/forum/showthrea...ing-28897.html
The only time a higher-rated automatic may make more sense is on the highway if the gearing is so much taller and you do the majority of your driving on the freeway.
Best advice: test both yourself in the same conditions on the same route!