Is my car’s autonomous emergency braking system faulty?

QUESTION

Hi John,

I recently purchased a new car from a reputable manufacturer. I am now working with the customer service department to get a refund. My reason for writing to you is to seek your views on the differences between AEB systems, and safety systems generally, from different marques. Given that this technology appears to be mandated for all new cars from 2025, it seems not all AEB systems are created equal.

The car I purchased appears to be set up to avoid "false-negatives" (AEB not activating when there is a threat) at all costs. This sensitivity seems to create "false-positives" (activating unnecessarily), which I consider are far more dangerous than false-negatives. False-positives take control away from the driver whereas false-negatives still leave the driver in control and able to avoid a collision.

My AEB activated in the middle of an 80km/h corner for no apparent reason. It braked so hard that if I had been towing an unbraked trailer, or had a car behind me, I would have been at risk of a serious accident. The advice from the customer service department was that I needed to over-ride the cruise control, and therefore the AEB, by accelerating (assuming my reaction time was that fast). This means having to accelerate beyond the speed limit in the middle of a corner. Or, of course, never use cruise control.

I suspect this manufacturer has set their AEB and related technology focused purely on city driving, or perhaps ANCAP ratings (which seem occasionally to produce perverse incentives), and have ignored the dangers it poses on Australian country roads. I haven't driven this car further than the local shops since the incident. Even then, I spend the extra time at start-up to turn off AEB and everything else I can think of before leaving the garage.

I recently spoke to the owner of a new vehicle from a different manufacturer. His ute's AEB and related systems seem to be much less "trigger-happy" and more in tune with being an aid rather than a danger. I haven't been able to find any definitive web information on the differences between brands and would be interested in your views to guide my future purchase.

Wouldn't it be good if we could alter the sensitivity of these systems and have our setting saved to a "driver profile"?

Without intending to imply anything specific about either manufacturer, a useful starting point might be to compare Subaru with Toyota. I’m particularly interested in Subaru Outback, Toyota Prado and Hilux on this issue.

Thanks for your help,

Peter

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ANSWER

Peter,

What vehicle is it? You’ve listed three - Outback, Hilux and Prado… There’s no need to be cagey about it - it’s not like a carmaker can sue you for defamation. You can’t defame a company or a car, under Australian Law - more technically, they can’t sue you for that.

Essentially, however, most modern cars ‘false positive’ all the time. In strict engineering terms, these systems are all operationally flawed. My Triton tells me I’m about to collide with parked vehicles regularly, in situations where there is zero chance of doing so.

The one redeeming feature - and it’s a big one - is that one day, AEB might save your life. Like, it’s a pain in the arse, but it also works.

Carmakers will say that this is an operational characteristic of the car. They’ll say it’s not defective and therefore you are not entitled to a remedy under Australian Consumer Law. And they will win. (I’m not a lawyer.) This is also quite a stupid situation. But think of the lifesaving benefit.

However, in my view, you are being melodramatic on the risk. All it does is apply the brakes. If you’re driving around a bend towing a caravan, at a speed where the combination would be unstable if you had to stop in a hurry, you’re driving too fast, dude. (Ditto if you were to accelerate slightly; you shouldn’t be on the raggedy edge, ever, while towing). Also, caravans have brakes. They don’t become instantly unstable if you brake in a bend, provided you’re driving conservatively.

I know you’re not going to like any of this. However, Consumer Law is not there to appease anyone's feelings, it’s there to compel the retailers of defective products to repair, refund or replace them (depending on the circumstances). Newtonian physics, pretty clearly, doesn’t give a shit how you feel about the speed you tow a caravan around a bend - it just delivers (predictable) outcomes. This is the universe we live in.

Also, you can’t really base a case for a refund on a hypothetical set of circumstances (‘if this’; ‘if that…’). Crashes that didn’t happen are worthless in this domain, they don’t count. Modern vehicles have a towbar installation integrated into the CAN bus (the car’s computer network). This tells the car a trailer is connected, and it invokes different dynamics-control systems, such as trailer sway control, etc. I would not be surprised if AEB was also adapted to conform to having a trailer installed on the car - I’m pretty sure it does in Subarus because I’ve checked this with the company in the past.

Certainly if the AEB activates and the car starts to yaw too much, or too little, then ESC would probably intervene also. What I’m saying is: You’re probably going to have to live with it.

John Cadogan

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