Tesla, Ford Receive ‘Poor’ Grades in Study of Driver-Assist Technology

Tesla and Ford Motor were among several automakers to receive poor grades in a study that reviewed driver-assistance systems, finding little evidence the technology provides safety benefits to motorists.

Car companies have been introducing more so-called partially automated driving systems, which control the vehicle’s steering and speed in certain situations, and sometimes allow hands-free driving. The study, released Tuesday by the Insurance Institute for Highway Safety, gave a “poor” rating to 11 of 14 systems it tested, concluding that most lack adequate measures to prevent drivers from losing focus on the road.

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

Only Toyota Motor’s Lexus brand earned an “acceptable” rating in the study, for its Teammate feature on the LS sedan, the industry-funded nonprofit group said. Two models received “marginal” ratings: General Motors’ GMC Sierra pickup truck, and Nissan Motor’s Ariya electric SUV.

Driver-assistance features on models from Tesla, Ford, Volvo, Genesis, Mercedes-Benz and BMW were given poor grades.

Vehicles equipped with driver-assistance features—such as adaptive cruise control and automatic lane centering—aren’t fully autonomous, and therefore require drivers to pay attention. Many use inward-facing cameras to monitor the driver and issue audible warnings if they become inattentive.

Regulators and safety advocates in recent years have raised alarm about drivers becoming too complacent on the road when relying on partially automated features.

IIHS looked at how the systems monitor drivers’ head or eyes, and how they issue attention reminders and emergency interventions if a driver doesn’t respond to those prompts.

The safety group said its new ratings are aimed at encouraging automakers to introduce more safeguards to prevent drivers from misusing the technology and to keep them alert behind the wheel.

“These results are worrying, considering how quickly vehicles with these partial-automation systems are hitting our roadways,” Harkey said.

Ford said its system, called BlueCruise, which allows for hands-free driving in some situations, includes many safeguards. The company said it disagreed with IIHS’s findings but would take them into account as it evaluates potential updates.

Tesla didn’t respond to a request for comment. Several of the automakers that received poor ratings said they were committed to safety and would take IIHS’s feedback into consideration as they further develop their systems.

Late last year, Tesla issued a recall to modify its Autopilot system in response to an investigation conducted by the National Highway Traffic Safety Administration, the top U.S. auto-safety regulator.

The automaker issued a software update to more than two million vehicles to add more alerts and controls aimed at keeping drivers attentive, after NHTSA said that Autopilot can be misused. Tesla has added new driver-assistance features and capabilities, including an upgrade it calls “Full Self-Driving Capability,” which is sold for $12,000 upfront or $199 a month as a subscription service.

Tesla tells drivers using Autopilot and Full Self-Driving Capability to pay attention to the road and to keep their hands on the wheel. The electric-car maker has long maintained that driving with Autopilot engaged is safer than doing so without it.

NHTSA has been investigating potential safety problems associated with driver-assistance technology sold by several automakers. The agency has no formal standards for advanced driver-assistance systems, but last year it proposed mandating automatic emergency braking on nearly all future cars and trucks.

Last week, the agency opened a probe into Honda over complaints from drivers using certain 2019-2022 models that their cars experienced “phantom” automatic emergency braking events.

Honda, whose technology wasn’t reviewed by IIHS, didn’t immediately respond to a request for comment.

Write to Ryan Felton at ryan.felton@wsj.com