[Tatsfield]

Once the car is out of warranty, I doubt whether Volvo carry any extra liability for Polestar optimisation installations. I suspect that you would have a hard time proving that Polestar blew up the engine and was therefore Volvo's liability. I also suspect that Polestar doesn't stress the engine to the point where reliability is an issue as this would increase claims during the warranty period, both original and subsequently possible Selekt second hand warranties. Police vehicles have these sort of Volvo power optimisations and there doesn't seem to be a history of failed police Volvos as far as I know.

All that I will say about Polestar is that, if you can afford it, it is a nice option to have.