• Driver-assist features have been available for 50 years
  • Autonomous (self-driving) cars are advancing all the time
  • The main difference is the level of driver control

Driver-assist systems have been available for decades, helping motorists stay safe on the roads. The next step is autonomous (or self-driving) cars, which take control completely out of human hands.

But how close are we to completely autonomous vehicles, and what are the differences between the self-driving cars being tested and the technologically advanced cars that are already available to consumers? Simon (@sheptinstall) breaks it down with the key statistics.

What is a driver-assist car?

Many of the cars currently on the road have automatic or intelligent features that assist drivers on the road.

These features are designed to improve safety and help motorists to make the right decisions. If you don't own a classic model, your car will probably have at least one driver-assist feature.

If not, you can install additional driver-assist features in most cars – the added advantage of this being that, by improving your car's safety, you can also reduce the cost of car insurance.

The first driver-assist systems in cars included cruise control, dipping mirrors and climate control. In fact, the first cruise control system was offered half a century ago – on the 1958 Chrysler Imperial.

Since then, we've seen automatic dipping lights, rain-sensing wipers, stop-start mechanisms, adaptive suspension and automatic emergency braking systems become commonplace. Now self-parking, lane-recognition and adaptive cruise control are accepted features on many new vehicles. 

A timeline of driver-assist features

What is a self-driving car?

Scientists and carmakers are working towards vehicles that will require no input at all from the humans inside.

In 2009, Waymo, part of Google, began testing and perfecting the self-driving car. In that short time, the company has developed self-driving vehicles that have covered almost two million miles.

Currently, Waymo's cars are driving on public streets with a test driver in the front seat. The driver is there to monitor the vehicle and report back, but also acts as a failsafe. In general, the tests have been a success so far – so don't be too surprised if you see a self-driving car showroom opening up in the near future. 

When can I buy a self-driving car?

The technology to ensure that self-driving cars are safe enough to go on the open market is still a few years away.

Manufacturers such as Volvo and Kia are testing 'self-driving vehicles', but, like Waymo, these usually still require the presence of a driver in case of emergencies – and are some way from passing all the government safety tests.

The first driverless car tested on the UK roads travelled at only 15mph and had a driver on hand in case anything went wrong – that was in October last year. In February, however, Tesla announced it had sold 200 of its latest self-driving cars to Dubai. The cars will operate as taxis in the wealthy, high-tech city from 2020. Even then, the cars will have a human driver ready at the wheel at all times.

An image of a self-driving car icon coming up to some roadworks with the text saying - 'self-driving cars struggle with unexpected events during a journey, such as encountering roadworks'.

The big difference between assisted driving and complete self-driving

It could be argued that, like self-driving technology, driver-assist takes partial control of your car – even though it's only for a short time. For example, the Intelligent Parking Assist System requires constant input from the driver to control acceleration and braking, but turns the wheel automatically.

However, it's the level of control that is all important. Although they're close, there are no cars technologically advanced enough to deal with every possibility drivers encounter on the roads. Self-driving cars always require a human failsafe, who can take control of the wheel if the car makes a mistake.

The problems arise with unexpected events during a journey. Imagine a construction zone that forces you to drive on to the wrong side of the road to get past, or a policeman waving you through a red light because of a fault. What about pulling over onto the pavement to let an ambulance get by? For a human, these are easy decisions to make, but for a computer it's much harder to override the normal rules of the road.

And what about spotting a sheet of ice, negotiating temporary makeshift road signs or reacting to a patch of broken glass in the road? The technology of a self-driving car needs to be so intelligent, it makes us realise what good drivers we humans already are.

A table showing the number of times Waymo test drivers had to take control of their self-driving car

When will self-driving cars be safe on our roads?

Testing is going on in many countries around the world, including real-world usage in cities such as Stockholm and Los Angeles. Manufacturers are claiming lots of positive results, although a few mishaps have been reported too.

Waymo, whose test drivers only had to take control of their self-driving cars 124 times in almost 635,868 miles last year, has carried out the most successful tests. But no authority is going to allow completely autonomous self-driving cars on their roads until the drivers never have to retake control.

Although self-driving cars are still some years off, the driver-assist technology that helps motorists stay safe on the road is very much available. It's even worth considering adding some of these features to your own car; they could help you avoid accidents, manage tricky manoeuvres and even reduce the cost of your insurance.