A Mercedes CLA's emergency braking system falsely triggered, causing a Tesla Model 3 to rear-end it. This happened during filming for a What Car? test, but there's more to the story than this one incident...

@whatcar The Model 3 was following too closely. Was it on FSD? Legally and practically, choose a following distance that allows for a panic stop by the lead car.

@whatcar This totally misses the point.

@wlmsears @whatcar If you can’t break fast enough to not rear end the car infront you are the one who fucked up not the car that made an emergency stop.

@TeslaJigsaw @wlmsears @whatcar Yes, but if you are rear-ended - potentially with far more severe consequences - when your car applies AEB incorrectly, the fact that it’s ‘the fault’ of the car behind is poor compensation.

@Jonas17751074 @TeslaJigsaw @whatcar We assign accountability to the agent who has control. The car behind controls following distance and attention. The lead car can't really do much, and spending time worrying about it is a poor use of resources. Modern cars provide good protection. If hit, might get a new car.

@whatcar My mercedes does something similar. Breaks suddenly in junctions or going down a hill, or cars turning front of me but I am passing them. I can only reduce sensitivity to low. I am not able to turn it off.

@whatcar Have you told Mercedes about this? How many times has it happened?

@whatcar I didn't. I tried with out issues and they don't bother to reply. To be honest i will sell the car next year. I know the trick now. Just touch the break very carefully and deactivate this thing. Red triangle goes and won't break. Like in junctions etc.

As a car reviewer who films so many EVs on road with a host of safety features, there is a reason we use a long lens. Amateur from @whatcar here. Way too close to be doing stuff with ADAS. I know the west is behind China in terms of general ADAS level amongst cars but come on, you're asking for an issue At the end of the day this is called an edge case...it not exactly normal for it to see a person traveling at 20+mph... It saw a person and stopped. Because people don't travel at 20+mph...So you'd assume it was like person. OH SHIT OH SHIT BRRRAAAKKKKEEEE! And that's fine. The only reason there was a crash was because the cars weren't driving at a safe distance for "filming" reasons. So really this is just a stupid situation. And so I’m fine with the Merc hard braking thinking there is a person there. You seem to think that it should be deciding if the person is running as fast an Olympian level of speed or not...You really want systems to think maybe people could just be running at 20+mph. It an absolute ridiculous "hot take" on a very niche edge case situation. Content for content sake. As for phantom braking at a junction...it happens. And it is shit when it happens. But hey, rather sometimes it phantom brakes cos it gets a bit confused then saying "oh I'm not so sure lets plough through whatever i think is there" It HAS to be on the overly cautious side. Apparently according to you it should just work perfectly all the time, and never make a braking decision wrongly. Great, except when it thinks its making phantom brake and ignores it then runs over a load of people... I think being a bit shit and sometimes braking when it doesn't need to is just showing where the system is, overly cautious cos FYI running over people isn't cool...

@whatcar Mercedes needs to be recalled

@whatcar Possibly. They at least need to take this seriously and not claim 'the system performed as intended'

@whatcar I think it's true. AEB and Lane keep assist tech has caused more problems and annoyances for me than it has saved me. I'm not saying to scrap it, but... Yeah

@whatcar Tuning could be better

@whatcar That's usually how we discover the complexity of automotive safety systems—through edge cases like this. What's the real-world trade-off between false positives and rear-end collisions?

@whatcar Well if Mercedes can only see crash data logged (not every AEB occurrence) numbers are unknown. Hence sharing the many concerned Merc owners experiences from the comments of the WhatCar vid. Something needs to happen.

@whatcar I get this regularly in my sprinter van!

@whatcar How regularly? For good reason or no?

Theres a place on the dual carriageway local to me and Its due to an undulation in the road when I go through it around 60mph the van thinks the road is no more as the van dips and slams on the brakes. This particular section is on a slight bend too. This first few times it happened its was very disturbing but now I expect it so its not a problem. If this happened on a Tesla people would be in uproar.

@whatcar Interesting how it went fully stop like that! 😳

@whatcar Some might say oversensitive and dangerous

@whatcar I would agree. Some of Tesla's phantom brakes have been sketchy, but I haven't witnessed anything like that.

@whatcar The Tesla which crashed in to the back or the Mercedes is not the Tesla’s fault It’s the drivers fault for driving too close to the rear of the Mercedes The most important safety feature of any car is the human brain and common sense.

@whatcar No comment on tesla failing to stop & break safely? Cmon fella

@whatcar If the Tesla rear-ends a car in front of it after emergency braking, the Tesla has reacted incorrectly. Either there was too little distance between the cars, or the automatic braking was too late.

@whatcar Im just about to go on the M25 & M23 I am amazed how little gap people give to vehicle in front. Strange because the gap is basically your living space

@whatcar Sorry to generalize but German’s don’t do complex software well. I have a Tesla. My wife has an Audi. I used to have a 2015 BMW 335xi that was great but that was before the era of these complex safety‘features’, lane keeping etc. Prove me wrong!

@whatcar Seems like an extreme off-case where a pedestrian is hanging out of the rear of the vehicle. Why didn’t the Tesla have adequate distance to stop?

@whatcar 'Unfortunately, not everything went to plan..'

@whatcar I thought Tesla's didn't crash?

@xTeslaJigsawCan you share more details so we stop guessing? 1. Uncut footage + telemetry from the Tesla behind Mercedes: drive mode, pedal inputs, speed when Mercedes braked? (We've seen Mark Rober's controversial Wile E. Coyote-style wall test: or search "Mark Rober Can You Fool a Self-Driving Car?" – tied to Luminar/LiDAR promo.) 2. Any Mercedes footage/telemetry showing what triggered the sudden brake? Speculation: - Tesla tailgating closely, accelerator down → AEB only mitigates at last second. - Mercedes might have seen the cameraman in open rear as a pedestrian and braked hard (edge case for their AEB?).

@whatcar Basically the Tesla tech works and the Mercedes tech is SHIT!!!!!!!

@whatcar Why drive so near you crash when the car in front hits the brakes?

@whatcar My brand new skoda hybrid did this a few times on the motorway, very dangerous, And Lane assist a nightmare too

@whatcar I’m actually a Tesla fan and long Tesla dominance in autonomous (and humanoid robots), but was the Tesla also on self driving or was a human driving it? Because if it was on FSD it should be able to brake in spite of any emergency or sudden braking by the car in front of it.

@whatcar My wife had the same experience with a Model 3 though. Came up to intersection, motorcycle waiting to cross , totally halted, the M3 made an AEB stop. Shouldnt happen, but it can

@whatcar It's Tesla's fault for not keeping the distance.

@whatcar My wife’s VW ID Buzz GTX slows on a 70 mph straight road abruptly and claims bend ahead. It also slams on emergency brake at low speed in car parks or when parking giving everyone in the car whiplash. There has been nothing within 3 ft when this has happened.

@whatcar I'm one of the people you mention who has a Tesla that brakes for no good reason on autopilot (usually entering a tunnel, but other situations also). That's scary enough. I can't imagine how scary full-on emergency braking while still under driver control would be!

@whatcar A driver/car can never cause a car to rear end it. That’s an oxymoron.

@whatcar So the Tesla failed to maintain a safe following distance.

@whatcar I’ve had this happen on a highway. BMW came to complete stop for no reason. Very scary. Those driver assists increase stress vs driving as a human as you never know what they will do

@whatcar My Tesla Model 3’s AEB (no, not AP phantom braking) has done more harm than good by unnecessarily slamming on my brakes multiple times in my years of ownership. Unfortunately, while it’s adjustable, it cannot be disabled unless AP is fully disabled.

@whatcar Why was the Tesla following at an unsafe distance? Was the driver overriding FSD.

@whatcar Shit, we recently bought a GLA for my wife. I wish I watched this video before buying it. 🤦‍♂️

@whatcar My model 3 did stop suddenly for no reason on at least two occasions. First it saw a pedestrian that was in no danger of being hit and the second time it was at an intersection that I slowed down for but the car thought I wasn’t slowing down enough and slammed the brakes.

@whatcar You may be on point but that camera in the trunk is emitting some AF energy, I would check to see if that tripped the Mercedes also... It emits IR and senses thermal I have heard and both can be confused by an IR distance emitter and a warm body hanging off the back of a car...

@whatcar Do you have to pay Tesla extra for the don't drive up the arse of the car in front mode?

@whatcar I have had phantom braking issues in my Tesla but only once to a full stop because someone in front of me slammed on the brakes. The other occasions were only a slight slow down.