Surely a muon scanner, as we know that cosmic particles can penetrate even San Francisco weather.Just hard too imagine that, given all those redundant sensors, that a Cruise would roll into something as huge as a bus. I mean, there are TMC posters who constantly remind us that the only good sensor is an additional sensor. Perhaps it's finally time for Cruise to install a gamma ray spectrometer. A gravitometer might have helped. A bus has a lot of mass.
A neutrino detector for certain edge cases, as soon as they beef up the vehicle suspension , and shrink it so it fits on Lombard Street.
A Yang particle detector, mainly for the Chinatown geofence.