The American Automobile Association (AAA) is warning drivers nationwide not to over-rely on advanced safety systems in cars, like automatic braking and lane assist systems, during inclement weather.
New research from the organization found that heavy rain affects safety features from functioning properly, which can result in performance issues.
During AAA experiments, vehicles equipped with automatic emergency braking, that traveled at 35 mph, collided with a stopped vehicle one third of the time.
"Often these systems are tested in somewhat perfect conditions," Greg Brannon, AAA's director of automotive engineering and industry relations, told ABC News. "But the reality is drivers don't drive in perfect conditions."
In the experiment, AAA simulated rain and other environmental conditions, such as bugs and dirt, to measure impact on the performance of various advanced driver assistance systems (ADAS).
To simulate rainfall, AAA engineers designed a system using a reservoir to hold water atop the cargo area of the test vehicle. The system was connected to a nozzle positioned above the windshield, so the spray pattern covered the entire windshield.
"We created a device that allowed the windshield to experience basically what it would in a rainstorm," Brannon said.
AAA also found that cars with lane keeping assistance departed their lanes 69% of the time.
"It's pretty, pretty substantial and surprising findings for something that is on a lot of cars today," Brannon said.
The tests were conducted with five different vehicles, including the 2020 Buick Enclave Avenir with automatic emergency braking and lane keep assist, a 2020 Hyundai Santa Fe with forward collision avoidance assist and lane keeping assist, a 2020 Toyota RAV4 with pre-collision system and lane tracing assist, and a 2020 Volkswagen Tiguan3 with front assist and lane assist.
According to the National Highway Traffic Safety Administration (NHTSA), "Driver assistance technologies hold the potential to reduce traffic crashes and save thousands of lives each year."
The agency said more than 36,000 people died in motor vehicle crashes in 2019 -- many of which were tied to human error.
Brannon said consumers should use advanced safety systems, but not in the place of engaged driving. "The most dangerous thing that a consumer can do is to over-rely on the systems."
"AAA's advice to consumers that have advanced safety systems in their car really is the same regardless of what that system is, and that's to drive the car like the system is not there," Brannon said. "Select a car that has the most advanced safety systems available, because they all hold a lot of potential to reduce injury and save lives, and that's a good thing,"
Brannon said drivers should never use cruise control during inclement weather, and he advised motorists to slow down.
"Really understand the environment that you're operating in and then make sure that you are fully engaged in that task of driving," Brannon said.