No, it is purely the engine power at the flywheel. The important thing is power to weight ratio. An Up weighs considerably less than a Polo so a 60bhp Up has a higher power to weight ratio than a 60bhp Polo and is therefore quicker.
The 75bhp engine in the Up gives more again and is much more lively than a 60 or 70bhp Polo.
I've just checked, a Polo Match 60PS weighs 1067kg and a Move Up weighs 929kg, so you can do the maths...
Edited by: Allybasher