— Adaptive cruise control and active lane-keeping systems help in certain vehicles much better than others, according to researchers at the Insurance Institute for Highway Safety (IIHS).
IIHS tested adaptive cruise control and active lane-keeping features on five models from four automakers, and all models were equipped with automatic emergency braking.
- 2017 BMW 5-Series (Driving Assistant Plus)
- 2017 Mercedes-Benz E-Class (Drive Pilot)
- 2018 Tesla Model 3 (Autopilot, versions 8.1 and 7.1)
- 2016 Tesla Model S (Autopilot, versions 8.1 and 7.1)
- 2018 Volvo S90 (Pilot Assist)
All the systems are supposed to keep the vehicles centered within marked lanes or use vehicles in front as guides. IIHS engineers tested the vehicles on curves and hills, but the Tesla Model 3 was the only car that stayed within its lane 18 out of 18 times.
Tesla's Model S also performed well but did overcorrect and crossed the line on the inside of the curve. However, IIHS says the other systems often required drivers to provide additional steering support to navigate the curves.
The Mercedes stayed within the lane nine out of 17 times and disengaged in one run, while the BMW stayed in its lane only three out of 16 times. In addition, researchers say the BMW was more likely to disengage than steer outside the lane.
The Volvo S90 stayed in its lane in nine of 17 runs and crossed the lane lines eight times.
But researchers determined hills posed a challenge to a system trying to see the road markings as the car crested the top of the hill. When the lines weren't visible, the Mercedes did well and stayed in its lane 15 times out of 18 and also constantly provided steering support without making any crazy moves.
The Tesla Model 3 did even better as it stayed in its lane all but once, but the Model S had more trouble on hill tests, staying in its lane only five out of 18 trials.
The Model S would swerve left and right until the system determined the correct location in the lane, leaving IIHS drivers "jolted" by the movements. The car also seldom warned the driver to take over and the Model S regularly went into other lanes or the shoulder.
The BMW and Volvo also didn't perform well, as the BMW 5-Series required drivers to override the steering as the vehicle went across lane lines on a regular basis. The Volvo S90 crossed the lane lines in two runs and disengaged in four trials as the vehicle crested hills.
Researchers say test drivers noted some vehicles would follow lead vehicles onto exit lanes even though the drivers didn't want that to happen.
Researchers concluded lane keeping systems do assist drivers, but questions remain about how much drivers should completely depend on the systems.
Adaptive Cruise Control
IIHS engineers used four different series of track tests to see how well the vehicles did with other vehicles traveling ahead, and how well the systems accelerated and slowed down.
Researchers found both Tesla models didn't perform well during 31 mph tests with stationary vehicles in front when adaptive cruise control was turned off but automatic emergency braking was activated. Only the two Tesla models hit the stationary targets.
With cruise control engaged, the Model S, Model 3, the Mercedes and the BMW avoided the targets, although both Tesla models braked before impact earlier than the Mercedes and BMW vehicles.
The Volvo avoided the target but braked more abruptly than the other models, with researchers describing the actions as "forceful."
IIHS emphasizes these were controlled track tests with drivers prepared to take control of the cars. Real-world highway driving could be much different with results not as favorable as seen at the track.