We don't really need 300KW+ when we could have 100RWKW or so from a V6. They get around in traffic pretty quick, after all.
But really, since when did a Yaris struggle to keep up around suburbia? The speed limits are only 60 anyway (50 if you are most Adelaide drivers)
A Yaris is pretty practical but I've even seen those little smart cars get around in a hurry when they need to.
Let's face it though, most of the time we're getting around on our own, why not a scooter?
But when traffic is banked up so badly, you're not getting anywhere anyway, so you could sail right past a 300KW HSV idling on the road on a pushbike.
But bikes in traffic can be a bit unsafe, not to mention looking a bit like a tard in all that lycra, so might as well walk.

I don't mean to troll, but this is a silly question on this website, really.