I don't think he is a particularly good economist. He frets about the misuse of resources for cycle/bus lanes and the time cost of the (arguably) true extra time it takes to drive as a consequence.
However, he misses a few other costs to the economy of the motor car. For example:
(1) the amount of lost work days caused by the 30,000 serious injuries - mostly motor car related - on our roads each year
(2) the cost of supporting an extra few percent of our population suffering from obesity related diabetes which threatens to overwhelm our health budget
(3) and, using his own argument, the amount of time his car (or the arrangements for managing his car such as traffic lights in locations that would not need them if there weren't cars - taking care to note that if we all cycled you'd need lights to regulate us in built up areas - holds me up and causes me lost time.
Its odd that he desciribes himself as a libertarian. I think secretly he is envious of the freedom that us cyclists have when he is locked up in his stationary metal box