Technical Phantom thud.

[Charnwood Fox]

For the second time in 3 months I've had a phantom thud.

Stationary at traffic lights, all of a sudden - THUD, as if someone had either hit me or thrown something at me. No-one about, no cars near enough to have hit me. No damage/marks on bodywork.

The sound seemed to come from my left. (RHD)

Anyone else experienced anything similar?
Car runs perfectly, everything seems to work fine.

 

[850kd]

Had exactly the same thing last week on the M1 about J21. Checked the car when I stopped at the services and can see no damage anywhere.
I have decided a stone must have got trapped in tyre tread and bounced of wheel arch protector.
I sometimes have my own driveway stones -nominally 20mm- caught in the treads of the pirellis, but they come loose as I drive onto the road, Im thinking at speed they would bounce out with a bit more force.

 

[Charnwood Fox]

If I'd have been moving I'd have thought road debris, but on both occasions I was stationary. I'm fairly sure no other vehicle was close enough or travelling fast enough to hit me with its debris, either.
On the first occasion I was surrounded - closely - on 3 sides by other stationary vehicles.

 

[bravo jtdM150]

something heating up (plastic) and popping in place, i get the odd thud (not very loud) from the dash area when it heats up? Does it sound mechanically related?

 

[Charnwood Fox]

It sounds like someone has thrown a snowball at a door panel.

 

[Hellcat]

Speaking from experience with something actually hitting the door panel - it sounds like the side of the car had been ripped off.

 

[Big Black Stilo]

if its happening just after you get in the car when you have the heater on and its just getting hot its usually the headliner or something in there expanding. both my bravo and 306 do it