> What are the continued operating costs [?] ... When I lived in Toronto I could have an all-access unlimited subway pass for $100 a month,

This does not speak to operating costs.

Mass transit fairs are usually subsidized from general tax revenues - user fees usually cover something like 10-25% of actual costs.

Right, this I'm aware of - so I'd be interested in seeing someone do some numbers on the real costs of highways vs. mass transit.

Last time I ran the numbers the US highway system costs around 3$/gallon of gas used on the highway system. So, double your gas costs, then add all the other costs and you can approximate the "net" cost of your commute.

It's more than your gas cost, though - there are other things like maintenance, amortized cost of car ownership, insurance, etc.

You don't just pay for gas, you pay for the car to put it in.