Like airbags and crumple zones, various car safety technologies are mandatory on new cars. While airbags are considered ‘passive’ safety tech – they only activate when you crash – Advanced Driver-Assistance Systems (ADAS) are ‘active’ and are intended to prevent you from having an accident in the first place.
With driver error a leading cause of road accidents in the UK, the best case scenario with ADAS features is that they prevent avoidable accidents. These include accidents where the driver unintentionally leaves their lane, is driving too fast or hasn’t spotted an obstacle ahead of them.
However, Which? has found evidence that these features are being habitually turned off by drivers, with just over half of drivers who have an ADAS feature on their car reporting they turn at least one feature off at least some of the time. And when the tech is off, it isn’t protecting anybody.
This highlights that there’s a lot of room for improvement in the way these systems are implemented and explained.
: see the models that aced our tough lab testsThe safety features drivers are turning off
In descending order, these are the features that survey respondents told us they turned off at least some of the time.
1. Speed assist
Depending on the system, speed assist uses on-board cameras, road-map data or a combination of both to tell you what the speed limit is. If you exceed the speed limit, an audible alert is played and, depending on the settings on your car, your speed may also be automatically adjusted. It’s often tripped up by road signs for parallel roads, unofficial signs, some digital signage and out-of-date map data from its on-board computer.
2. Lane-keep assist
On-board cameras and sensors detect lane and road-edge markings and cajole the driver into staying in their lane (see graphic, bottom). It’s typically deactivated when using indicators. Lane-keep assist tends to get caught out on narrow roads and often ignores cyclists or parked cars. Emergency lane keeping is required by law and should only activate when the car is going to cross a solid white line.
3. Automatic emergency braking
Radar and lidar systems detect pedestrians, cyclists and other vehicles, and will stop the car to prevent a collision (see graphic, top). The latest legislation adds rear cross-traffic braking (when you’re reversing). Additional pedestrian and cyclist-detection scenarios will be added at a later date.
4. Attention/drowsiness monitoring
Cockpit cameras detect the position of the driver’s eyes and other facial features. The system will audibly warn the driver if their attention isn’t on the road for an extended period of time. It also gives a warning if it detects symptoms of tiredness, such as yawning or slow blinks.
5. Blind-spot monitoring
Sensors detect when an object – most often another vehicle – is in the driver’s blind spot. The system flashes a visible warning until the object is no longer present. Some will vibrate or give an audible warning if the driver indicates to move towards the object or starts to leave their lane.
*Percentage of drivers who turned the system off at least some of the time, based on our representative survey of 1,584 UK car owners in January 2025.Safety tech turn-off
When done right, safety systems have the potential to reduce avoidable accidents. The European Commission cites figures that lane-keeping systems could reduce the number of injuries from crashes caused by a car leaving its lane by 20% to 30%. But sometimes it can take just one incident for a driver to completely lose faith in their car’s safety systems. And when they lose faith, they turn the systems off.
Since day one, she’s found it constantly misreading speed limits (such as advising her the limit in a 30mph zone is actually 80mph) and unnecessarily correcting her steering as she crosses over centre lines when navigating parked cars around town. ‘To feel the steering wheel suddenly spin and the car begin to swerve was terrifying,’ she recalls.
Eileen tells us she’s ‘seriously considered getting some old, beat-up car from about five years ago that doesn't have this technology’. Hyundai told us it regularly conducts real-world testing and, where possible, introduces software improvements to address customer concerns.
: we reveal the best EVs for all budgetsEU regulations
There are four key ADAS systems legally mandated on new cars in the EU as part of the General Safety Regulations (GSR and GSR II). While the UK isn’t part of the EU, the rules apply to Northern Ireland and will soon be adopted in Great Britain. In any case, most UK cars already use software designed to work both here and in the EU.
GSR and GSR II require intelligent speed assist, driver drowsiness and attention warning, autonomous emergency braking and emergency lane-keep assist. The latter two are required to kick in only to avoid critically dangerous situations. All four must be activated by default whenever the car starts, so even if you turn it off on one journey, it will be on the next time you set off.
Euro NCAP specifications – which aren’t a legal requirement – go further. But manufacturers can choose how many features they add, balancing the number of Euro NCAP points they score with customer needs and cost. The more features you add, the more points you get. For example, lane-keep assist (where the car guides you back to the centre of your lane in a non-emergency situation) isn’t mandatory, but a car will lose points for not having it or for not activating it by default.
This means that it’s rare to find a new car in the UK where lane-keep assist and speed assist aren’t on by default, even if they don’t perform well in the real world. With many cars, it’s not possible to just turn off lane-keep assist while keeping the emergency function on.
What’s gone wrong?
Legislation and Euro NCAP specs allow room for manufacturers to interpret how to implement these systems, which means every car is different.
Done well, ADAS should collaborate with the driver and, when it gets things wrong, make it easy for the driver to override it.
He explains: ‘We’re looking at what is the safest, most insurable vehicle, rather than which one gives the least number of false interventions and the best driving comfort. Often we have issues because those are two conflicting goals’. In other words, a car that has ADAS set up to intervene sooner is inherently more insurable, but also more annoying to drive.
However, it’s demonstrably possible to create a system that satisfies both of these seemingly opposing needs. High-end cars such as top-spec versions of the BMW i5 have vast arrays of sensors, cameras and on-board computing power.
They have also gone through extensive on-road training to learn the various ways in which road markings and signage are designed, maintained and positioned.
Cheaper cars – or, according to Al-Ani, models from some brands that are newer to the UK – may trip up more often due to a lack of local training and knowledge. For example, he cites one unnamed and new-to-the-UK brand that didn’t have its car set up to recognise the UK’s national speed limit sign when it went through assessments on UK roads.
Other common problems include unofficial 5mph signs being interpreted as 50mph (standard British road signs are in increments of 10mph) and weight limits being interpreted as the speed limit, with ‘3 t’ becoming ‘30’.
The NCAP issue
Which? helped to found crash-safety organisation Euro NCAP in the 1990s, and we take its safety test results into account in our car reviews. But if these safety features pass Euro NCAP tests while also being annoying in real life, does it indicate that the testing isn’t up to scratch?
In an effort to avoid this in future, Euro NCAP is adding a significant real-world driving portion to its tests from January 2026 onwards and will take driver-friendliness into account.
That’s not by accident: Dacia told us that while it takes safety ‘extremely seriously’, its aim is ‘not to produce cars just to be rewarded Euro NCAP stars, particularly if that means fitting vehicles with features and technologies, like some ADAS, that our customers don't want to use and/or pay for today’. Given how well its budget-friendly cars sell in the UK and across Europe, that strategy seems to be working.
In response to our findings on people turning off ADAS, in particular lane-keeping systems and speed assist, Euro NCAP’s technical director Richard Schram said the organisation is ‘technology neutral’ with the simple – if somewhat broad – aim of zero unintentional lane departures. ‘Some of the implementations have proven overly aggressive and/or intervening against the driver’s will, creating additional risks and annoyance,’ Schram explained.
He was also quick to add that Euro NCAP doesn’t mandate speed assist’s incessant beeping – blame the European Commission for that one – and that the organisation hopes ‘the unacceptable audible warnings … will be overturned’.
A brighter future ahead?
Thatcham’s Al-Ani is optimistic about cars launching in the near future and has been impressed when testing plenty of upcoming models. ‘Lane-keep systems are massively improved,’ he explains.
And it’s not just established carmakers achieving this: ‘We’ve even seen new market entrants doing very well with collaborative, very gentle and not overly intrusive lane-keep assistance.’
So the future looks a little brighter, but for the people living with cars that veer them off course on a daily basis, that’s scant consolation.
If your current car is from the 2010s or earlier, you probably won’t have experienced the current state of ADAS. The quality of these features can have a huge impact on your day-to-day driving, so getting to know how they work is crucial.
Learning to live with car tech
Michael Passingham, Which? senior researcher
In the three months before this article was published, I drove 11 different cars.
It’s a privilege but, as I’m a recent addition to the Which? Cars team, it’s been something of a culture shock to go from my 2018 car to the current crop of vehicles that adhere to the latest EU and Euro NCAP specifications. I’ve had cars brake for non-existent crossroads, jitter me around on country lanes and inform me that I’m driving 50mph over the speed limit.
I can see why so many people reach for the ‘off’ button at least some of the time on all these tools. But I’ve also learned to live with them – or ‘collaborate’ with them, as Thatcham’s Al-Ani put it.
While each car is different, it doesn’t take me long to get used to their foibles and understand where I need to pay extra attention. Even when they’re wrong, these systems don’t let you switch off your brain, which is a good thing.
That doesn’t exonerate brands that haven’t put in the work on UK roads, though, and it’s also up to legislators and standard setters to ensure that their rules and assessments meet real consumer needs.
If ADAS is turned off, it isn’t protecting anybody. And that’s bad for everybody
: how the latest tech aims to protect you and other road usersMake safety tech work for you
If you’re new to ADAS, getting used to how it works is key.
Choose roads where there are frequent speed-limit changes and also find those where you’re able to drive at more than 40mph, as this is when some features kick in (particularly lane assist).
If you find that some features aren’t working to your liking, find out which can be turned off and how to do so. If you find that turning off a specific feature is fiddly, consider whether you can live with this on a daily basis.
Some cars let you configure how certain systems behave (such as changing the way the vehicle reacts to drifting over road markings) or the threshold at which speed warnings kick in. However, be aware that in order to comply with legislation or Euro NCAP guidance, these settings may return to their defaults when the car is started again. This depends on the age of the vehicle and when it was approved for sale.
If you’re buying a car online, ensure that the money-back guarantee will give you enough time (and miles) to thoroughly check the functionality of the ADAS systems.
It’s important to get in as many miles as you can to see how ADAS behaves in your car. Under the Consumer Rights Act, the seller of a new car must repair or replace a faulty car. However, with ADAS issues – which can be driver and location-specific – you’ll need good video evidence, and records of when and where problems occurred. Set up cameras (such as dash cams) that show you, the steering wheel and the road ahead to capture as clearly as possible when the car misbehaves.
Drive smarter and cut costs using our expert advice.
This article first appeared in the March 2025 issue of Which? magazine.source https://www.which.co.uk/news/article/is-technology-ruining-new-cars-aGVAU5Q3JD6u