Not an Audi owner, so apologies for gatecrashing the forum, but I have a VAG car and the exact same thing just happened to my Skoda Roomster 1.6 TDI this morning and police, fire services and insurance company are completely baffled.
The car was last driven Saturday 11/1/2015 evening with sub-zero temperatures here in London, after a long drive down from the North. No problems, no fault alerts, not problems with the drive or the car, all working super smoothly.
This morning (Monday 13/1/2025) police arrive at the door at 8.10am to report my car round the corner was on fire and asking me to attend the scene.
Like the original post, fire broke out spontaneously in the engine bay at around 7.30am when passers by called the fire service and police.
Passenger cabin and fuel did not catch fire, but the front is entirely burned out and the front of the car is on the ground. Tires suspension all gone.
Police asked for CC-TV footage and said that at around 7.15am the alarm goes off, and then shortly after there are flames and smoke.
Waiting for recovery and removal now, after speaking to the insurance.
Thinking that before the alarm went off, even a short-circuit would have not been possible if the electrics were off. Could the alarm have made the electrics come on and then there was a short-circuit or would the alarm go off because there was a fire?
I am wondering if, like the original poster, some water had got in somewhere and frozen and then with the thawing today triggered some electrical fault.
Old trusted car with plenty of millage, so fear there will be very little from the insurance for it.