Driver-assist and autonomous cars: what’s the difference?

3 minutes

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Driver-assist vehicles have been available for decades, but what are the differences between self-driving cars and driver-assisted cars - and who's responsible for road safety?

  • Driver-assist features have been available for over 50 years, helping drivers stay safe on the road
  • Who's responsible for road safety in an autonomous car - the driver or the driving system?
  • Did you know that autonomous (self-driving) cars are already on the road?

What is a driver-assist car?

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

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. 

In 2018, a proposal was outlined by the EU that would require all new cars built in 2021 and onwards to have a number of mandatory safety systems built in. 

What is a self-driving or fully autonomous car?

A self-driving car is a vehicle that requires no input at all from the humans inside – and they’re already on roads in America.

In 2009, Waymo, part of Google, began testing and perfecting the self-driving car. This year, they began test-driving on public roads without anyone in the driver’s seat. 

The cars were judged to be safe enough for this after they travelled over 350,000 miles in total with only 63 disengagements. A disengagement is when a self-driving car either hands over control to a safety driver, or a safety driver takes control, when the car can’t or doesn’t deal with a situation safely. 

Who’s responsible for an accident in an autonomous car?

This is a working progress in the UK, but recent recommendations by the Law Commissions suggest that human drivers shouldn’t be legally accountable for road safety in an autonomous car. Transport Minister Trudy Harrison said the government would "fully consider" the recommendations. In autonomous cars, the driver should be redefined as the "user-in-charge", so if anything goes wrong, the company behind the driving system would be responsible, rather than the driver. However, if any sort of monitoring is required - in extreme weather conditions, for example - it shouldn’t be considered autonomous and therefore current driving rules should apply. So in summary, a user-in-charge can’t be prosecuted for offences linked directly to driving task (like dangerous driving, speeding or running a red light), but they will be responsible for other tasks such as insurance and checking people are wearing seatbelts.


When can I buy a self-driving car?

Self-driving cars may be on the open road in the US, but they’re not yet ready for the open market.

Manufacturers such as Volvo and Kia are testing 'self-driving vehicles', but, unlike Waymo, these usually still require the presence of a driver in case of emergencies.

GM appear to be the established motor manufacturer closest to launching a self-driving car to the consumer market, claiming that they are developing the technology. However, like Waymo, their self-driving cars will form a taxi fleet.

It’s yet to be determined when we’ll be able to park our very own self-driving car in the driveway – or, rather, when it will park there itself.  

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.

But it's the level of control that’s the crux. Assisted driving cars will always require a driver; self-driving cars can be completely empty and still negotiate the streets.

So, why isn’t the UK ready for self-driving cars? It’s more about legislation than technology. 

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

Testing is going on in many countries around the world, including the UK. However, before fully autonomous cars hit our country’s roads, since 2018, the government have been carrying out a three-year review. This review will determine whether the UK’s road laws are suitable for self-driving cars – not, significantly, whether the technology is there yet.

Matthew Avery, chief research strategy officer at Thatcham Research, which was involved in the consultation, said: "In the next 12 months, we're likely to see the first iterations of self-driving features on cars in the UK."

"It's significant that the Law Commission report highlights the driver's legal obligations and how they must understand that their vehicle is not yet fully self-driving"

In 2021 the Department for Transport gave the green light to automated lane-keeping systems (ALKS), the first type of hands-free driving to be legalised in the UK. So, although total self-driving cars we can buy are still a little way off, the driver-assist technology that helps motorists stay safe on the road is very much available. It's 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 car insurance.

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