Tesla launched its robotaxi service in Austin on Sunday as its Model Y vehicles drove around a select batch of riders who gave rave reviews about smooth, convenient rides that were available for the cheap price of $4.20 .

While no one was in the driver's seat of the Tesla robotaxis, a front-seat rider acted as a "safety monitor" during the trial.

The company has begun a test run of the driverless cabs, years after CEO Elon Musk vowed they would be on the road.