A consortium that includes SoftBank Group is in late-stage talks to invest $1 billion or more in Uber Technologies Inc.’s self-driving vehicle unit, according to people familiar with the negotiations, a move that would help the ride-hailing firm make its pitch to investors ahead of its eagerly anticipated IPO.

Under terms being discussed, SoftBank’s Vision Fund and other investors, including at least one unnamed auto maker, would take a minority stake in the unit at a valuation of between $5 billion and $10 billion, the people...