Stop the free ride: all motorists should pay their way, whatever vehicle they drive
(theconversation.com)
That make sense.
Also, an hybrid vehicle may pollute more if it's never recharged and only use gas. Or less if it's frequently recharged.
So an added benefit of that change would be to get rid of an automatic insentive for hybrid. Taxing gas and fossil fuel is a more direct and efficient insentive. If gas cost more, hybrid owners will recharge more often.