One would hope that when you have a Bowers and Wilkins system in your car, they are actually using the speakers they develop. Most systems are really about the amp and DSP, not so much the speakers. I used to change out my speakers and add in an Amp and DSP in the old days but as much as I cycle through cars, I stopped doing that and just go for the higher end system as they sound better than then base system. Typically, I go test driving, get a great offer and trade on the spot, don’t have time to get the system out and the dealer wants to charge me for taking it out or change the deal.
I checked out some Volvo’s with the B&W system, while nice sounding when it being driven, on the road, the road noise tends to be high for that vehicle. The Bang and Olufsen system in the Audi is ok and depending on the source, it might sound shrilly or muddy. I have to admit I don’t plug in much in that car, I just use the Bluetooth. I’ll plug in when I want to listen to music with a better quality sound. I think the DSP manages the Bluetooth sound fairly well so, I’m good.