He didn't say it was due to more efficient motors. Just compare the average MPG of the cars on US roads, running on subsidized gasoline, vs. those on European roads, running on heavily taxed gasoline.
An interesting question for this is will governments start with 'electricity tax'. There will be a ~$40bn revenue hole from cars swapping to electric in USA. Even proportionally more in Europe and Australia where the fuel taxes are much higher.
