Well, we've yet to see a speed vs. fuel consumption chart for the CVT-equipped Mirage.
I expect it will outperform the manual on the highway with its much taller gearing at cruise. Wayne at CleanMPG is testing one this week - hopefully we'll see some numbers soon.
If that's confirmed, then drivers who spend most of their time on the highway (above ~70-80 km/h) should get the CVT car for best MPG. Urban/suburban drivers (ie. the non-brain dead kind, willing to eco-drive) should get the manual.
I wrote about this on MirageForum:
Mirage CVT or 5-speed: which should you get for best gas mileage/fuel economy? )
Though in reality the difference in volume of fuel consumed between the two amounts to a hill of beans, and the "payback" on the CVT has to be taken into account if the decision is purely financial.