Local democracy isn't inherently more virtuous than a larger, centralized democracy. Local municipalities can be very provincial in their thinking, like blocking housing for future residents.
Except the Tories have always made a big deal about 'local democracy', and opposing 'centralization'. In rhetoric and in theory at least (while in practice they have consistently destroyed local democracy and centralized power at every opportunity).
Hence he's now telling the elected representatives of Londoners that they can't put the interests of the majority of local residents (who, in inner London at least, are overwhelmingly non-drivers) ahead of those of the minority (and those from outside London) who want to speed through their streets pumping poisonous crap into the air.
He's _imposing_ car use on people who don't want it.
Actually surprised at myself - given I already detest the guy and his party for their economic policies alone - at the degree to which being told I have to accept his class of people speeding through my streets and further polluting the air I have to breath, and that I'm not even to be allowed to vote democratically to prevent it, infuriates me. It feels much more personal, like a physical attack.
He really is a sociopath. I don't believe there's even any thought-through ideology behind this, still less any morality - it's simply the only thing he can think of doing to increase his chances of 'winning' (i.e. of avoiding total wipe-out in the next election, by appealing to one small segment of the population, the fervent petrol-heads). The Uxbridge byelection result gave him the idea, and it's all he has, so he's doubling-down on it.
It's the finance-sector guy in him, working out what will maximise his chances of personal career advancement. The bigger picture, i.e. the well-being of other people, doesn't even register for him. He has to be the most out-of-touch PM we've ever had (his family wealth makes most Tory PMs, even, look like paupers)