Self-driving cars are being tested by a major manufacturer on UK public roads for the first time.
Nissan is testing prototypes of its Leaf model with enhanced autonomous driver technology on busy routes in east London.
The Japanese company is clocking up more than 300 miles as it develops fully autonomous vehicles with the aim of making them widely available by 2020.
Three Leaf cars are being taken on 25-minute round trips from the ExCeL exhibition centre to Beckton.
This involves a number of challenges, including roundabouts, lane changes, pedestrian crossings and speeds of up to 50mph.
But the Leaf cars have avoided collisions as they have 12 cameras, five radars and four lasers enabling them to identify surrounding objects and calculate their position on the road to within a few centimetres.
There is also a driver who can take control in case of an emergency.
Tetsuya Iijima, Nissan's global head of autonomous driving, said: "The reason we're focusing on autonomous driving technology is safety.
"Around 93% of accidents come from the driver. If a machine replaces human manoeuvres 90% may be reduced.
"Safety enhancement is the first motivation."
Single-lane autonomous driving will be featured in Nissan's Qashqai from next year, with fully so-called driverless cars on the market two years later.
But as Mr Iijima conducted one of the east London tests, he warned the vehicles available in 2020 will have "some limitation".
He told the Press Association: "In scarcely-populated traffic the driver can be relaxed.
"We can explain to the customer, in that situation there's almost nothing you need to do.
"In this area (of east London) the driver needs to pay attention because the vehicle is not perfect."
Small-scale tests of driverless car technology have previously been conducted in locations such as Milton Keynes, Greenwich and Bristol.
Last month, the Department for Transport (DfT) announced innocent casualties from driverless car crashes would be protected under new insurance rules.
A single-insurance product will be required to cover both a motorist when they are driving as well as a car when it is in an automated mode.
This will mean people hurt in driverless car crashes that were not their fault will have "quick and easy access to compensation", the DfT said.
The measures, which follow a public consultation, were set out in the Modern Transport Bill.
A DfT study published in January predicted that driverless cars could increase congestion on some UK roads for several years.
Delays on motorways and major roads during peak periods were expected to rise by 0.9% when one in four cars were automated, researchers said.
Early models of driverless cars were expected to operate more cautiously than regular vehicles, resulting in "a potential decrease in effective capacity and a decline in network performance", the report warned.
The analysis suggested that a reduction in congestion might not be achieved until automated vehicles made up 50% to 75% of traffic.