I passed my driving test at the fourth attempt. You might think that means I'm not as safe as someone who passed first time. But would you feel safer with no driver at all? Maybe not, and it's for this reason that automotive firms have included driver-assist functions in their prototype driverless cars. This allows the human driver to take over if there is a problem.

Google is one manufacturer that has prototype driverless cars. These have been retrofitted with steering wheels and conventional controls to allow normal driving. But this is just a stage - the vision is to have fully automated cars very soon. The director of Google's self-drive project, Chris Urmson, hopes his 11-year-old son will never have to take a driving test. To achieve that, the cars need to be on the roads in five years. He says driverless cars will drastically reduce accidents and traffic jams.

According to Chris "Some 1.2 million people are killed on the roads around the world each year. That number is equivalent to a jet falling out of the sky every day."

He thinks gradual changes to existing car designs are not enough to deal with the problem. "If we are really going to make changes to our cities, get rid of parking lots, we need self-drive cars," he says.

Google's prototypes have racked up over a million kilometres on the road. They have also had to deal with unexpected situations, such as a child driving a toy car in the road, and a woman in an electric wheelchair chasing a duck. In each case, the car reacted safely.

Some are not convinced. Sven Beiker of Stanford University thinks driverless cars will still need human input in extreme circumstances. He also worries that people may forget how to operate their vehicles if they do not do it regularly. I guess I shouldn't throw away my driver's licence just yet.