Because we are utterly predictable when it comes to engine choices, TopGear's default advice - with just the merest handful of exceptions - is that you should opt for the most powerful and/or torquiest you can afford. However, the C3 is one of those exceptions.
Not because this, the most powerful engine in the C3 range - a 1.6-litre four-pot putting out 120bhp - is anything but Really Quite Good. It is. It'll manage 60mph in a respectable nine seconds while returning 48mpg. It revs cleanly. It's nice and quiet.
But it isn't - how to put this? - necessary. Because the C3 isn't about going fast. Or even moderately rapidly. There's nothing wrong with the way the C3 behaves on the road - actually, it's nicely composed and sensible - but there's nothing in its responses that encourages you to hunt out any of those red-lining, grip-enveloping clichés.
So, unless you're inexplicably set on owning the fastest C3 on sale, you're probably better to stick to one of the hyperfrugal diesels - 74.3mpg if you opt for the greenest variant - and bask instead in the agoraphobia-inducing charms of that massive panoramic roof and the Citroen C3's general sense of MPV-esque airiness. If you want your supermini's handling to be dripping with zing and zest and pizzazz and other things containing the letter ‘z', mosey on over to the Fiesta... or the DS3.