I think you are right to be wary Simon.
The Aero has a glass rear windows so ,thankfully,is OK - but a couple of years back I experienced problems with the plastic rear window on our Smart car.
As you describe, it was a very cold, frosty day.I had washed the car and was very
gently polishing the back window with some Renovo - when it split top to bottom and my hand went straight through
I managed to find a Smart specialist who stitched in a new window panel - as the cost from Smart/Mercedes for a replacement was truly scary
I am now ultra careful when it turns cold; lesson learnt.....
James
