I use my 436HP all the time in the car (hooked to car stereo speaker). Excellent P25 decode while moving on most P25 channels here in Los Angeles and Orange County. Better than my HP1, PRO-106, WS-1080, and BCD396XT with regard to P25 decode quality. PRO-106 and WS-1080 both have more treble audio (which I like), but on weaker P25, especially, with the WS-1080, I get a lot of Donald Duck sounding audio. They miss a lot of what the 436HP seems to pick up. Even with no bars on some signals, P25 decode is usually good.
Recently bought the HP-2, but have not used that in the car yet. I never have used any of my base units like 536HP, 996XT, or GRE-600 in the car.
If I could only have two scanners out of my list below in signature, it would be the 436HP and 536HP. If only one, then the 436HP for portability.
Steve AA6IO