[ghaff]

I haven't personally done the math but my understanding is that the current (possibly subsidized) rate for Lyft/Uber is in the $1.00 to $1.50 per mile range. The IRS rate for car usage is about $0.53/mile.

Presumably the cost for a heavily utilized vehicle is going to be lower per mile. OTOH, any commercial fleet service is going to have costs on top of the base mileage cost. (The $0.53 figure also ignores any distance the vehicle might have to travel to pick you up.)

So it's probably reasonable as a back-of-the-envelope swag to assume that, if a fully autonomous vehicle were available today, you could probably undercut a "ridesharing" service by about 50%. It's definitely not suddenly going to be almost too cheap to meter just because you take the driver out of the equation.