The EPA rates (highway, 5 speed manual) the G5 XFE, a high mileage model we don't get here, at 6.7L/100km, (or 42 Imp MPG). For comparison, the Corolla gets 6.4 (44 Imp. mpg) and the Civic gets 6.9 (41mpg). So it's basically competitive. Driving style will make more difference than the difference between models.
Also from the EPA the Aveo5 gets 6.9L/100km (Imp 41mpg), the same as the Fit and less than the Yaris 6.5 (43 Imp. mpg)