VED is simply a tax like any other - set in large part to (a) raise income for public spending, and (b) modify behaviours (eg encourage the purchase of low or zero polluting vehicles)

There are very few taxes which are hypothecated (allocated for particular purposes).

Any promises made pre-election are probably worthless - how would you prove that the VED was additive, or merely replaced other sources of Treasury funding that were reduced.

The only hope is that road maintence backlog will be a priority post the Covid crisis as (a) it improves the infrastructure, and (b) it could create lots of jobs quickly to offset rising unemployment.

I think you'll find it'll increase and go nowhere near road improvement.

It is going for road improvements. Paying for pedestrianising streets. Paying for cycle lanes. Increasing parking costs.

Perhaps better than the early Victorian system where every parish was expected to maintain the roads ?

In a sense it's not that different now. Except for the Trunk Road network road maintenance is down to counties/unitary councils. In the last 20 years hundreds of miles of A road have been 'de-trunked'. While funding was given to the councils the amounts were and remain inadequate.