Spending the extra money from increased fuel and vehicle sales taxes on public transport would be great for city dwellers in general.

Reduced minimum cost of living for the poor, less traffic for those who drive for a living or have no choice or are willing to pay for luxury.

Rural poor would struggle, they'd need support through another means.

I don't like the idea of extra tax complexity when it could just be an adjustment to headline rates though. Too much admin and potential for benefits cliffs.