iDSI (with the CVT transmission) actually has a surprising amount of low-end torque - some say better than VTEC - as it is designed for city driving. is very efficient on fuel - in fact should be better than Vios although i think is really neck-and-neck depending how u drive the car.
VTEC a bit slower off the mark but make up for it at higher revs. certainly higher performance than Vios . slightly less FC than iDSI version but still quite good.
Email me u want to take a look at the cars as i am a SE at Kah Motors (Ubi showroom).
[email protected]Cheers

Joanne