Phantom Bike Spotted by ACC - Caused Severe Braking on Motorway

[Chris H]

I've used the ACC quite a lot on my S5 Trophy and generally like it, it's pretty good at leaving appropriate (adjustable) distance and smooth slowing when someone cuts you up etc, but this is new and a bit weird.
I was driving along the motorway with ACC set at 68mph, passing something on the left, nothing in front of me in my lane and suddenly the car braked quite hard - not an emergency stop by any means but enough to have caused problems if a car had been behind on a busy motorway. I couldn't see anything in front, though I had just gone over a white forward arrow painted on the road - I wondered if the car thought it was a vehicle or something. I didn't have time to look at the display so don't know what it had 'seen'. A bit later it did the same again; no white arrow this but I did look down at the display a there was a picture of a pushbike in blue colour straight ahead. There was nothing on the road for a long way, but there was a motor bike way, way ahead. The picture of the blue bike continued to display on the screen in the lane ahead even when the motor bike went even further ahead and changed lanes. Then my car braked again, at which point I turned ACC off and didn't use it for the rest of the journey. On the way home I did use ACC several times with no issues.
Question: Why was it 'seeing' a bike in the road when there wasn't one?
I'm wondering if there's something that detects pushbikes and then makes the car slow down much earlier because it's assuming the bike will be travelling very slowly.
Has anyone else had this?

 

[DBedford]

MG ACC always switched off on our ZS, worst piece of 'Tech' ever!

 

[Ian Key]

Were you heading into sunlight? I wonder if that confused the camera?

I tend to use manual cruise control especially on a dual carriageway with slip roads or service roads displaying a lower speed.

 

[OzDrew]

Yeah, I've experienced the same sudden braking when using ACC, when the car thinks it's seen any kind of bike (motor or otherwise). Have never managed to catch what's on the display, it dissappears too quick. First thing I look at is my mirrors.
It's the first car I've ever had where I hover my foot over the accelerator, instead of the brake, while using cruise control.

 

[Alb]

I tend to use manual cruise control especially on a dual carriageway with slip roads or service roads displaying a lower speed.

I've never found manual cruise control and can find nothing about it in the manual.
How do you access this?

 

[emmrecs]

I've never found manual cruise control and can find nothing about it in the manual.
How do you access this?

I agree, but perhaps a "careful", controlled use of right foot??

 

[Garmor]

I've never found manual cruise control and can find nothing about it in the manual.
How do you access this?

I think that seems more like the Speed Limiter which recognises speed limit signs and you can switch between auto and manual, not the ACC.

 

[Ian Key]

I've never found manual cruise control and can find nothing about it in the manual.
How do you access this?

Sorry. Early morning brain fart. My MG4 had manual cruise control. I mean I tend to use the manual speed limiter when the roads are busy or there is a chance of the car seeing speed limits for slip roads etc.

 

[T1 Terry]

Our poverty pack MG4 gets scared by big trucks on the other side of the road as we approach a left hand bend in the road, I've learned to keep the foot on the throttle when I see the possibility of this MG freakout event happening, it's real scary with a B triple or A double right behind you doing a similar speed, there is zero chance it's going to slow down before at least a few axles have passed over the poor scared MG .... so one of those things where you need to be aware of your surroundings and be aware of the times the ACC freaks out .....

T1 Terry