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New IIHS test: One out of 14 partial automated driving systems tested rate acceptable

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The Insurance Institute for Highway Safety (IIHS) has created a new ratings program that it says should encourage automakers to incorporate more robust safeguards in their partial driving automation systems.

One vehicle out of the first 14 IIHS tested under the new program earned an acceptable rating. Two rated marginal and 11 rated poor.

IIHS noted that vehicles with partial automation are not self-driving even though automakers sometimes use names that imply their systems are. The driver must still handle many routine driving tasks, monitor how well the automation performs, and remain ready to take over if anything goes wrong.

While most partial automation systems have some safeguards to help drivers stay focused and ready the initial tests show that they’re not robust enough, IIHS said.

“We evaluated partial automation systems from BMW, Ford, General Motors, Genesis, Lexus, Mercedes-Benz, Nissan, Tesla, and Volvo,” said IIHS President David Harkey, in a news release. “Most of them don’t include adequate measures to prevent misuse and keep drivers from losing focus on what’s happening on the road.”

The Teammate system, available on the Lexus LS, was the only system to earn an acceptable rating. The GMC Sierra and Nissan Ariya earned marginal ratings. The LS and Ariya each offer an alternative system that earned a poor rating.

The Ford Mustang Mach-E, Genesis G90, Mercedes-Benz C-Class sedan, Tesla Model 3, and Volvo S90 systems earned poor ratings, in some cases, for more than one version of partial automation.

The ratings only apply to the specific models tested even though systems with the same names may be used on multiple vehicles from the same manufacturer, IIHS said.

“Some drivers may feel that partial automation makes long drives easier, but there is little evidence it makes driving safer,” Harkey said. “As many high-profile crashes have illustrated, it can introduce new risks when systems lack the appropriate safeguards.”

Today’s partial automation technology, including Tesla’s Autopilot and GM’s Super Cruise, and feature bundles that provide similar capabilities use cameras, radar, or other sensors to “see” the road and other vehicles. Adaptive cruise control (ACC), lane centering, and various other driver assistance features are combined to provide partial automation, IIHS said.

Research has shown that drivers who use these systems tend to drive faster, tend to look away from the road more frequently and for longer periods of time, and tend to engage in more distracted behaviors,” Harkey said.

ACC maintains a driver-selected speed but will automatically slow to keep a set following distance from a slower-moving vehicle ahead and then accelerate when the way is clear. Lane centering continuously adjusts the steering to help the driver keep the vehicle centered in the travel lane. Automated lane changing is also becoming more common.

“The shortcomings vary from system to system,” said IIHS Senior Research Scientist Alexandra Mueller, who led the development of the new program. “Many vehicles don’t adequately monitor whether the driver is looking at the road or prepared to take control. Many lack attention reminders that come soon enough and are forceful enough to rouse a driver whose mind is wandering. Many can be used despite occupants being unbelted or when other vital safety features are switched off.”

The new IIHS ratings are meant to encourage safeguards that can help reduce intentional misuse and prolonged attention lapses as well as to discourage certain design characteristics that increase risk in other ways, such as systems that can be operated when automatic emergency braking (AEB) is turned off or seat belts are unbuckled.

Scores are awarded based on a battery of tests conducted over multiple trials, and some performance areas are weighted more heavily than others.

When possible, tests are conducted on a closed test track. For certain tests that must be conducted on public roads, a second IIHS employee sits in the front passenger seat to monitor the driving environment and the vehicle systems.

In some cases, manufacturers are already making changes to their systems through software updates, which may result in adjustments to the IIHS ratings. The two Tesla systems evaluated, for example, used software that preceded the most recent recall in December 2023.

IIHS expects improvements to be rapid.

“These results are worrying, considering how quickly vehicles with these partial automation systems are hitting our roadways,” Harkey said. “But there’s a silver lining if you look at the performance of the group as a whole. No single system did well across the board, but in each category at least one system performed well. That means the fixes are readily available and, in some cases, may be accomplished with nothing more than a simple software update.”

IIHS says effective driver monitoring is essential to making partial automation safe, meaning systems should be able to detect if the driver’s head or eyes are not directed at the road and whether the driver’s hands are on the steering wheel or ready to grab it if necessary.

To evaluate this, IIHS engineers record what happens when the lens of the driver monitoring camera is blocked, the driver’s face is obscured, the driver is looking down, and the driver’s hands are not on the steering wheel. For systems that allow hands-free driving, the engineers also record what happens when the driver’s hands are holding a foam block the approximate size of a cell phone. Systems should not activate under these conditions. If they’re already switched on, they should issue an alert.

None of the 14 systems meet all these requirements, although the Ford systems come very close.

Ford BlueCruise and Ford Adaptive Cruise Control with Stop & Go and Lane Centering Assist immediately issued alerts when the driver’s face or the camera lens was covered, but failed to detect when the driver’s hands were occupied with another task.

The BMW system didn’t react when the camera lens or driver’s face was covered, and the Mercedes-Benz system lacked a driver-monitoring camera altogether. However, both vehicles detected when the driver’s hands weren’t on the steering wheel.

Timely and persistent attention reminders are also key, IIHS said. When a partial automation system detects that the driver’s eyes aren’t directed at the road or their hands aren’t ready to take over steering, it should begin a dual-mode alert, such as an audible and visual warning, within 10 seconds. Before the 20-second mark, it should add a third mode of alert or begin an emergency procedure to slow the vehicle, IIHS said.

Lexus’ Teammate, both Ford systems, and GM Super Cruise meet those requirements. When the test driver deliberately looked away from the road and held the foam block in both hands, Teammate began audible and visual alerts after four seconds and began an emergency slowdown procedure after 16 seconds.

Both the hands-on Nissan ProPILOT Assist with Navi-link and hands-free ProPILOT Assist 2.0 systems as well as Tesla Full Self-Driving performed almost as well, IIHS said.

The hands-on Nissan system provided audible and visual alerts about six seconds after driver disengagement, but it didn’t provide a third type of alert until around 21 seconds had passed, when it pulsed the brakes. Seven other systems didn’t provide dual-mode alerts within the first 15 seconds.

Partial automation systems need appropriate emergency escalation procedures to minimize the danger to occupants and other road users if the driver doesn’t respond to those attention reminders, IIHS said.

Regardless of how many different modes of alerts they issue, systems should begin a slowdown procedure within 35 seconds of driver disengagement. Drivers who ignore alerts for this long are either in distress or misusing the system. The system should send an SOS message to emergency responders or a 24-hour help center, and the driver should be prevented from restarting the automation for the remainder of the drive, IIHS said.

Of the 14 systems tested, only GM’s meets those requirements.

Five systems include two of the three emergency procedures, and five include one. Lexus’ combination of Dynamic Radar Cruise Control with Lane Tracing Assist system and the two Genesis systems all fail to take any emergency action if the driver disengages from driving and does not respond to repeated warnings.

Another group of requirements is aimed at ensuring drivers stay involved in decision-making. All lane changes should be initiated or confirmed by the driver. When traffic causes the ACC to bring the vehicle to a complete stop, it shouldn’t automatically resume unless the system can confirm the driver is looking at the road and no more than two minutes have passed.

The lane-centering feature shouldn’t switch off automatically when the driver makes manual steering adjustments within the lane as that can discourage drivers from being physically involved in the driving, and physical involvement can help prevent mental disengagement.

More systems performed well in these categories than any of the others. GM Super Cruise and Tesla Full Self-Driving are the only ones that will make a lane change without any driver input, IIHS said. Super Cruise and both Tesla systems are the only ones that switch off lane centering when the driver does any manual steering.

Many systems allow ACC to resume automatically after a stop of more than two minutes or when the driver is not looking at the road, IIHS said. Both Tesla systems and BMW Active Driving Assist Pro will resume ACC in both scenarios, for example, while several others will restart in one of the two situations. Volvo Pilot Assist is one of seven systems that will not automatically resume in either scenario.

“There is little evidence that partial automation has any safety benefits so it’s essential that these systems can only be used when proven safety features are engaged,” IIHS said. “These include seat belts, AEB and lane departure prevention.”

To achieve a good rating in this category, a partial automation system shouldn’t switch on if the driver is unbelted or AEB or lane departure prevention isn’t active. If already in operation and the driver unfastens their seat belt, the system should immediately begin its multi-mode, driver-disengagement attention reminders. It must also be impossible to switch off AEB or lane departure prevention if the automation is engaged.

The hands-free ProPILOT Assist 2.0, Lexus Teammate, and GM Super Cruise systems are the only ones that meet all these requirements, according to IIHS.

The hands-on ProPILOT Assist with Navi-link and the BMW system come close, but each deactivates without issuing an alert when a key safety feature is disengaged. This is dangerous because the driver may not be aware that they need to resume full control of the vehicle, IIHS said.

In contrast, most of the systems fail multiple safety feature requirements. Volvo Pilot Assist, for example, deactivates without an alert when the driver unbuckles, can be activated with lane departure prevention turned off, and also remains active if the feature is switched off mid-drive. The two Genesis systems fail all safety feature requirements.


Featured image: IIHS test driver of automation systems (Credit: IIHS)

The 11 partially automated driving systems that are rated poor under IIHS’ new test. (Credit: IIHS)

IIHS test driver of automation systems (Credit: IIHS)

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