Took me a sec, but I went through my Pete stuff and found this from Pete's infrastructure proposal January 2020:
He will require his DOT to propose a new and sustainable user fee-based system, such as a vehicle-miles-traveled fee with appropriate privacy protections that is already being piloted by states and can potentially replace the gas tax. Within such a system, discounted rates can be offered on a sliding scale based on income.
Not a straightforward answer, I know. And the VMT issue honestly never came up during campaigning for me. I would believe the "appropriate privacy protections" bit means no tracking or electronic monitoring, but self-reporting mileage. I can't say for sure that is what Pete meant, just my opinion of what Pete would support after input from individual state DOTs.
Anyways, all of our discussion about this is moot. No VMT or gas tax raise will accompany the infrastructure package being released tomorrow by POTUS.