Autonomous Cars, Buyers' advice, industry, Motoring News, road safety

MasterTips: Is current autocruise too dangerous?

  • Some írksome, others called ‘dangerous’
  • No consistency between tested vehicles
  • Some models failed to respond to parked vehicle
AUTO CRUISE CONTROL: Reports from America recommend ''don't trust it!''
AUTO CRUISE CONTROL: Reports from America recommend ”don’t trust it!” Image: Suppied

Just when many road safety ‘experts’ are beginning to feel that autonomous vehicles will address this issue ”once and for all” others are questioning it. Insurers in the US believe adaptive cruise control is unsafe. – SA motoring group Master Tips

JOHANNESBURG, Gauteng – Just when may road-safety ”experts” are beginning to believe that autonomous vehicles will address the issue ”once and for all” others are questioning whether such an optimistic approach is a premature.

The Insurance Institute for Highway Safety in the US, where use of autonomous vehicles is fairly advanced, tested several premium cars and concluded that some were ”irksome”, others were ”downright dangerous”.

The study examined a 2017 BMW 5 Series’ Driving Assistant Plus, a 2017 Mercedes-Benz E-Class’ Drive Pilot, a 2018 Tesla Model 3, a 2016 Model S’ Autopilot (versions 8.1 and 7.1) respectively, plus the 2018 Volvo S90’s Pilot Assist.


Each vehicle’s autobraking was rated ”superior” by the IIHS but only the two Tesla models passed a test involving driving towards a stationary vehicle target with adaptive cruise control off and autobrake turned on.

The same test was repeated with ACC switched on. Then the 5 Series, E-Class, Model 3 and Model S, braked earlier than with emergency braking, avoiding the target.

However, the owner’s manuals for all these vehicles warn ACC may not brake when it encounters stationary vehicles entering its sensor range.

Worst of all, test engineers noted instances of each vehicle except the Model 3 failing to respond to a stationary vehicle.


IIHS senior research engineer Jessica Jermakian reported that when she tested the Mercedes-Benz’ ACC it briefly detected a stationary bakkie. Then, however, it lost sight of it and sped ahead until she braked.

She added: “At IIHS we are coaching to intervene without warning but other drivers might not be so vigilant. ACC systems require drivers to pay attention to what the vehicle is doing at all times and be ready to brake manually.”

The IIHS also found the Tesla Model 3 braked unnecessarily. The car unexpectedly slowed 12 times during a 290km drive: seven were for tree shadows on the road, the others oncoming vehicles in other lanes or vehicles crossing the road far ahead.

Jermakian warned: “Unnecessary braking can pose crash risks in heavy traffic, especially if it’s more forceful. Plus, drivers who feel that their car brakes erratically may choose not to use adaptive cruise control and would miss out on any safety benefit from the system.”


Overall, the tests suggested current ACC systems were not ready to handle speed control in all traffic situations.

The organisation then tested the systems’ active lane-keeping capabilities. Only the Tesla Model 3 stayed in lane on all of its trials. The Model S performed similarly but over-corrected on one curve, causing it to cross the line on the inside of the curve.

None of the other systems in the test provided enough steering input on their own to consistently stay in-lane.

The Mercedes-Benz stayed in lane nine out of 17 times but strayed to the lane marker in five trials. The system disengaged itself in one trial and crosses the line in two.


The BMW stayed in lane only three out of 16 times and was more likely to disengage than steer outside the lane.

The Volvo stayed in the lane nine out of 17 times and crossed the lane line eight times.

With intervention to avoid potential trouble, active lane-keeping systems on BMW, Volvo and Tesla Model S units all disengaged. Their steering assistance only resumed after the driver re-engaged autopilot.

Another issue as a tendency by some to follow a lead vehicle into the exit lane in slow traffic.


Chief research officer David Zuby said: “None of these vehicles is capable of driving safely on its own. A production autonomous vehicle that can go anywhere, anytime, isn’t available at your local car dealer.

”You also won’t find one for quite some time. We aren’t there yet.”

Such findings should also serve as a warning to those using adaptive cruise-control at the moment. Do not accept their intervention as a given – it still pays to pay attention and focus on the task of driving irrespective of technology.

*The report from the US did not contain comment from the automakers involved.

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