Automakers are delivering major improvements in their automatic emergency braking systems following the latest discussions surrounding AEB laws.
In Australia, all new vehicles will need to include AEB technology from March 2025 following legislation introduced in 2023, a design rule that has the potential for some OEMs to end imports of non-compliant models.
Australian laws this year will relate to vehicle to vehicle avoidance in the most common rear end class of collision and will step up to include vulnerable road users such as pedestrians and cyclists by 2026.
Automakers have developed the AEB systems following the introduction of a tougher front crash prevention evaluation by the Insurance Institute for Highway Safety last year.
IIHS president, David Harkey highlighted the rapid progress manufacturers have made to improve these vital crash avoidance systems is impressive.
“Vehicles that excel in this new test will save lives, as it addresses the most dangerous kinds of front-to-rear crashes,” Harkey says.
Twenty-two of the latest 30 vehicles evaluated earned a good or acceptable rating, which requires systems to be able to prevent or substantially mitigate crashes at higher speeds. In April, only three out of the first 10 small SUVs tested performed to that level.
The Acura ZDX, BMW X5, BMW X6, Cadillac Lyriq, Chevrolet Blazer EV, Genesis GV80, Honda Prologue, Hyundai Santa Fe, Kia EV9, Kia Sorento, Lexus NX, Subaru Forester, Toyota Camry, Toyota Crown Signia and Toyota Tacoma all earn good ratings for their standard systems. The Mercedes-Benz E-Class is available with an optional system that also earns a good rating.
Higher speeds, multiple targets
According to the IHHS, the original vehicle-to-vehicle front crash prevention test was run at 12 and 25 mph (20 and 40 kph) with a passenger car target in the centre of the travel lane. It was discontinued at the end of 2022, as all vehicles tested were earning the top rating of superior.
The updated test includes trials run at 31, 37 and 43 mph (50, 60 and 70 kph). In addition to a passenger car target, it examines performance with a motorcycle target and a semitrailer. Vehicles are tested with the semitrailer centred in the travel lane and with the car and motorcycle targets centred and offset to one side.
As a result, the new evaluation reflects a greater proportion of police-reported front-to-rear crashes, including many that tend to result in serious injuries or fatalities. More than 400 people are killed annually in rear-end crashes with semitrailers, for example, while rear impacts account for more than 200 motorcyclist deaths per year.
The trials using targets evaluate both the systems’ forward collision warning and automatic braking capabilities. If the test vehicle fails to achieve a minimum speed reduction at the slower test speeds, only the forward collision warning system is evaluated in the higher-speed tests. In all the test runs using the trailer, only the forward collision warning system is evaluated, and the test driver steers out of the lane to avoid a crash.
Points are awarded for warnings that occur at least 2.1 seconds before the projected time of impact and for substantial speed reductions in the AEB tests. Speed reductions account for two-thirds and warnings account for one-third of the maximum possible score.
How the vehicles performed
The good-rated systems delivered timely forward collision warnings and came to a complete stop before impact in all the trials with the passenger car target. They also met those performance standards in most trials with the motorcycle target and provided timely warnings in all the trials with the semitrailer.
A few vehicles didn’t manage to stop before hitting the target in one or more of the motorcycle test scenarios, though they slowed substantially before impact. Several more were one- or two-tenths of a second late in delivering forward collision warnings with the motorcycle target.
For vehicles that did not rate as well, the motorcycle tests were the most common stumbling block.
Overall, the acceptable-rated systems brought the equipped vehicles to a complete stop before impact and delivered timely warnings in a large majority of the trials. However, their performance was subpar at higher speeds, especially with the motorcycle target. They all failed to prevent a collision with the motorcycle target in the 43 mph test scenarios, in some cases hitting the target at speeds of more than 25 mph.
All the poor-rated vehicles hit the motorcycle target in the slowest, 31 mph, test with the target centred. Some barely reduced speed or did not issue timely warnings.
The poor-rated vehicles also struggled in the tests with the passenger car target. Most failed to slow enough in the 37 mph test with the target centred to qualify for additional AEB testing. However, in most trials with the passenger car and semitrailer, they delivered timely forward collision alerts.