Google car, self-driving
Nissan manager believes autonomous cars will be helped by humans, even long after the steering wheel is removed Google

Even autonomous cars without steering wheels will still need the guiding hand of a human to deal with unfamiliar scenarios - and they will need to know how Germans and Italians drive very differently.

That is the thinking at Nissan, whose general manager of advanced planning, Stewart Callegari, spoke to IBTimes UK at the Geneva motor show.

Likening the proposed system to that of air traffic control, Callegari explained how Nissan's work with Nasa and technology used by its rover could lead to autonomous cars calling for help from a remote 'mobility manager' when they get into difficulty.

"When the car recognises that it's stuck it would contact a mobility manager who will then understand the conditions, interpret the data and draw a path for the car to follow."

An example of when this system would be needed, Callegari says, is when a broken-down car blocks the autonomous vehicle's path ahead, and double white centre lines in the middle of the road technically forbid overtaking the stricken car.

Once the autonomous car has been guided around the problem, this scenario and its outcome will be uploaded to the cloud and downloaded to the knowledge bank of all other self-driving Nissans - a process called fleet learning.

Callegari added: "We have [partially] autonomous planes now but they still have ground control to speak to during complex situations. That's a key aspect [to autonomous car development]. When you've got these trick situations you will probably still need some human interaction in order to make things work properly - at least until the roads are completely, completely different."

Do you drive in Italian or German?

Another challenge faced by autonomous cars is how to navigate different countries and around humans using different forms of etiquette.

Callegari explained how self-driving cars will need to be taught how human driving and behaviours differ by country, and adapt accordingly.

"Blatting down the Autobahn at 250km/h (155mph) is quite common in Germany, then you'll get chased down by a Mercedes or a Porsche. Then in Italy you'll have someone in a Punto doing the same thing, but the driving conditions and the expectations there are quite different."

In other words, autonomous cars will need to be comfortable with moving quickly in Germany, where lane discipline is generally very good, but in Italy they will need to deal with far more erratic driving from locals.

Callegari went on: "People don't really tailgate in the UK; you think it's bad there but it's not that bad. But here [Switzerland] people tailgate, it's just part of the way you drive. They sit two metres off your bumper and the conditions are very, very different in those cases...also how people drive, how aggressive they are, how casual they are is very different. In [rural] US it's very relaxed but around the M25 it's completely different."