Towards the end of the video he addresses the point that the optimum speed of cars is around 60(or I thought it was 70).
This argument doesn’t apply here because that figure is for a car traveling at a constant speed on a straight, flat road with no wind. E.g. a freeway/motorway. In a city, a significant amount of the energy is used to speed up and slow down at intersections.
Remember the kinetic energy formula, Ek=1/2 mv^2 . That tells you that accelerating a car to twice the speed takes 4 times the energy, or in other words it takes 4 times as much fuel to get to 60 as it does to get to 30.
This extra energy to get up to speed is going to far outweigh any benefit from less rolling resistance at 60 compared to 30.
Zagorath