Self-driving car software startup NuTonomy hopes to have a fleet of vehicles “moving people around as a service” next year, CEO Karl Iagnemma said on Tuesday at The Information’s autonomous vehicles summit.

Those cars will require a human "safety driver" in the car in case anything goes wrong, at least initially. When fleets can run without those drivers “is the big unknown in this space,” he said. NuTonomy, which has raised about $20 million in venture capital, has told its investors that it is 97% of the way toward its goal, but that the final 3% will be the hardest part.