[chiph]

Depends on the design, YMMV, etc. etc. But Consumer Reports found that the Ford Fiesta and Mazda 3 returned 1 mpg better when specced with an automatic.

http://consumerreports.org/cro/2012/01/save-gas-and-money-wi...

If you choose the CVT in the Nissan Versa, you'll get 5mpg better economy over either the manual or the automatic choices.

http://www.edmunds.com/fuel-economy/five-myths-about-stick-s...