Burning a gallon of gas generates 20lbs of CO2 (most of the weight is the O2), so 100 gallons produces a ton. Direct air carbon capture should cost roughly $100 per ton at scale, so the fee should be $1/gallon of gasoline (either at vehicle purchase or at the pump).

That’s completely affordable and lower than current gasoline taxes in many places.

If we made that one change (and funneled the revenue into carbon capture) existing ICE cars could be carbon negative in 5-10 years, and, as we phased them out (because EVs are just better) we’d have a clear path to pre-industrial atmospheric CO2.