If I want to provoke people I say that we should substantially reduce the amount by which we subsidise car owners.
There are various measures that I would potentially be in support of, which would involve financial disincentives for drivers in certain situations. Slapping a load of extra tax on petrol would be a very blunt instrument because it would affect people regardless of the necessity of their car use. I would prefer to look at road-pricing schemes because they could be tailored to make things a bit more expensive in areas where there is an issue with congestion, or where there is good provision of alternative modes of transport. It could also be adjusted according to vehicle type and provide a way to make sure, for example, that tradespersons weren't penalised by measures aimed at reducing unnecessary car journeys. It could also make it easy to buildin allowances for people travelling for medical reasons and so on.
I actually think a proper road pricing scheme could do away with the need for things like the closures we're currently looking at. But in order to do so, it would have to be a much more extensive system than people seem likely to accept. Road pricing was proposed in this country some time ago but was resoundingly rejected by the populace. Sadly. Of course, we do have one very crude version of it in the London congestion charge.