Street view cars all work during the daytime. There is no nighttime street imagery on streetview, and anecdotally, I've never seen a streetview car at night.
Having self-driving cars during daylight hours only is still an ambitious goal, though.
I don't think that would matter. Googles driverless cars use 3D laser scanners which don't require any ambient light. Plus, computers can theoretically see a lot more of the spectrum and therefore see a lot more than we mere mortals. They could look at the road ahead an know exactly what temperature it is, and possibly even see black ice. They could see a ninja on a black horse, at night, in the rain and fog, from miles away using thermal imaging.
Daylight driving, to a machine, would probably be more difficult than night time driving simply because there's more stuff happening on the roads during the day.
Street view cars all work during the daytime. There is no nighttime street imagery on streetview, and anecdotally, I've never seen a streetview car at night.
Having self-driving cars during daylight hours only is still an ambitious goal, though.