Uber Technologies Inc. will begin expanding a fleet of 100,000 autonomous vehicles powered by Nvidia Corp. technology starting in 2027, an ambitious move that could help bring down the cost of offering hailable robotaxis to consumers.The announcement builds on an earlier partnership the two companies struck in January, with Uber agreeing to offer some of its driving data to help improve Nvidia’s artificial intelligence models and chip technology that carmakers can use to develop autonomous vehic...