The whole debate on CO2 emissions from vehicles is completely flawed and this is just another extension of that. The idea that in order to reduce CO2 emissions we need to be driving bigger cars is the complete opposite of reality. A huge percentage of journeys are 1 person sat in 1.5-2 tonnes of metal. In cities all that inherent crash safety is irrelevant at speeds well under 30mph.
My view is that if there was genuine desire to reduce CO2 emissions (and air quality in cities), we would legislate for a new class of vehicle - 1 or 2 seats, 300kg, 50mph, half the width, powered tow-pods to put goods or kids in something like that. Smaller than the original Mini and work towards removing other vehicles from city roads over time. Cheap, practical, minimum weight being moved around and would allow for doubling of the number of lanes.
I live in the Countryside, commute 20 miles 2-3 times a week, so my second car does next to no mileage and is completely over the top for what it does. There's no real alternative though. I would get a motorbike if they weren't a pain in the cold/wet and if someone wouldn't knock me off. My local garage is a Can Am dealer, so I looked at them, not in any seriousness, but even second hand they're £8k! So I'm obviously sticking with my £1k Lexus IS200.
Going back to the original article, I don't think it's really right. I learned to drive 20 years ago, even then we all learned in Civics and Almeras and the like, there was only really the Ford Ka that was much smaller and that's still a decent size. The VW Up replaced the VW Fox which was bigger, the reality is that these small cars have only been around for a few years, other than the Smart Car. I'm ignoring the Toyota IQ because no one bought one.
As someone who likes Minis essentially because they're small, this topic annoys me because the 'right' answer would give us some genuine modern versions of the Mini.