After US organisation Consumer Watchdog made what it claims were “repeated calls for disclosure”, Google is now releasing monthly reports on its self-driving cars, which will detail the number of accidents said vehicles have been involved in.

Google’s report for May 2015 said that during the six years the self-driving car project has been running, a total of 12 minor accidents have occurred over the 1.8 million miles driven.

The search giant notes that this mileage includes both autonomous and manual driving of the cars, and that none of these accidents were caused by a self-driving vehicle itself.

In fact, many of the mishaps simply involved Google’s vehicle being rear-ended by another driver when stationary at traffic lights or a junction.

It certainly seems like a pretty impressive safety record on the face of it, although Consumer Watchdog still believes Google needs to publish more information and be more open about its driverless vehicles.

John M. Simpson, Consumer Watchdog’s Privacy Project director, commented: “We now know a few more details of what happened. The problem is that it’s Google’s version and they want us to take their word for it.”

The organisation wants the official accident reports to be aired, and not just Google’s view of the mishaps.

Simpson added: “Google is dribbling out bits information in the hope to silence legitimate calls for full transparency. They are testing on public roads and the public has a right to know exactly what happened when something goes wrong.”

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Google currently has 23 Lexus RX450h SUVs driving themselves around California, most of them tootling about in the Mountain View area where the company’s HQ is based. Nine prototype vehicles are also being trialled off public roads on private test tracks.