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 .

Tesla Inc. shares climbed after the automaker rolled out its long-promised driverless taxi service to a handful of riders, a modest debut for what Elon Musk sees as a transformative new business line.

Tesla has started giving rides in driverless Model Y SUVs in Austin. Details are still sparse, but limited service is open to vetted and invited riders.