Why this obsession with 'need' being the be all & end all, as though cars were a means of getting from A to B, period. They're not. Obviously. With cars, as with any other commodity, there's need and there's want, and why shouldn't someone be able to buy a car they want rather than merely one they need, any more than I should be prevented from buying a fedora hat, just because I want one? No-one needs a fedora hat. Should they be banned?
Ah, but cars kill people, hats don't. Fair enough. Is there any evidence to show that cars that can do 0-60 in 4 seconds, or have a top speed of above 80mph kill more people than cars that don't? Not in absolute terms; obviously they don't in absolute terms, because there are comparatively so few of them. But even in proportion to, say, the miles that are driven in them? In short, are fast cars actually more dangerous to other people than other cars? If they are, then there might be a case to argue. But I very much doubt it. I would guess that drivers of Porsches tend on the whole to be quite good and careful drivers, who are well aware of things like insurance premiums. I would guess there's a much stronger correlation between, say, age & dangerousness than car power & dangerousness. You'd probably have a far better impact on accident statistics by banning all 70 years+ people from driving. (How many of them, after all, really 'need' to drive?) I could be wrong. But that at least would be a case worth arguing.
But the idea that nobody 'needs' a nice car, so they should all be banned other than for use on test tracks, is fatuous, and just reeks of a kind of killjoy, humourless, hair-shirt sanctimony that alienates cyclists from (a large part of) the rest of society, and makes them think we're 'not living on the same planet'. All of which feeds that all-too-endemic 'I hate cyclists' mentality, which does none of us any favours.
By all means attack people for driving stupidly, dangerously, inconsiderately. But don't attack nice cars per se, purely on the grounds of being unnecessary. Nice cars aren't necessary, but they are cool. Like fedoras.