It's been almost a year since Google unveiled its quirky prototype self-driving bubble car, which has so far been confined to closed testing on private roads. Now, however, the company is ready to let the high-tech contraption loose on California's public roads. Google says "a few of the prototype vehicles" will be driving around Mountain View this summer.

Those worried about any potentially dangerous hiccups happening during testing—especially given the recent questions surrounding Google's safety record—will be pleased to hear that the cars will always have a human inside, and will sport a removable steering wheel, accelerator pedal, and brake pedal in case manual control is required. They'll also be capped to a gentle 25mph.

Google's also drawing on its experience with its self-driving Lexus RX450h SUV fleet, which has been roaming the streets of California since September of last year. According the the company, that fleet has logged nearly a million autonomous miles on the road, and is currently clocking up around 10,000 miles per week. Google says the totality of its logged autonomous miles are equivalent to "75 years of typical American adult driving experience."

The prototype bubble cars will build upon the software and experience from the Lexus fleet when they take to the road. This public testing, Google says, is "the necessary step, to getting them to drive themselves." It's also a significant one for public perception and acceptence. There's already a concern that self-driving cars and the like won't be as safe as human drivers, despite evidence to the contrary, and public tests that allow the public to interact with the cars will go some way towards alleviating those fears.

Google went on the offensive earlier this week after it emerged that four out of the 50 self-driving cars on Californian roads had been involved in accidents, and three of the four were the company's own Lexus SUVs. "Over the 6 years since we started the project, we’ve been involved in 11 minor accidents (light damage, no injuries) during those 1.7 million miles of autonomous and manual driving with our safety drivers behind the wheel," wrote Google's Chris Urmson in a recent post on Medium, "and not once was the self-driving car the cause of the accident."