the 2012 and up are best for mileage possibly over 40mpg hwy. the automatics are rated better than the manuals. there are some reliability issues with the automatic (dual clutch automated manual).
the 2005 to 2011 are good too. manual is better than the automagic.
May 2014 ROTM
for auto-x: '04 Liquid Grey ZX3
for street: '02 Infrared SVT