SAN FRANCISCO—General Motors’s venture capital arm has invested millions of dollars in Oculii, a startup maker of software for radar sensors used in self-driving cars, Oculii co-founder Steven Hong said. GM can use Oculii’s low-cost software to boost the resolution of radars and scale up its partially automated vehicles and full self-driving cars, he told Reuters in an interview. The investment is a “fantastic signal they’re serious about the technology and bullish about radar in general,” said the Stanford University graduate who founded Oculii with his father, Lang Hong, an engineering professor at Wright State University. He declined to disclose the financial details. Tesla Inc. eliminated radar sensors from its volume models this year, rekindling questions about the safety and performance of its advanced driver assistant system. Radars, which measure the distance between objects, enable a car to accelerate or brake to match its speed with that of the vehicle …