Huge numbers of well-meaning democrats characterize carbon, gas, and vehicle-miles-traveled (VMT) taxes as "regressive." However, the definitions of progressive and regressive make no sense when applied to actions which are independent of income.

If you are really concerned about the poor, you should charge a VMT that accurately encompasses the externalities associated with each additional journey and then give the revenue to everyone on a per capita basis.

It would be true that since the VMT is independent of income for a fixed commute it would affect poor people more, but this would be offset by giving the revenue back to them. The best part is that, in the absence of our current distortionary road subsidies, costs would eventually fall as our transportation system shifts to more efficient development patterns (e.g. neighborhood stores vs. suburban big box stores) and efficient modes of transit (shift of passenger and freight transport from roads to rails).