This may have been noted, but I just kind of noticed this right now.
We know the PP system has been weird, but one of the reasons I just saw is due to the update removing tires from the equation.
Apparently, the initial patch with PP set your points to their value with whatever tires the car had. When the next patch hit, it removed it, but didn't update the value in your garage listing. You can see the update value by 'opening' the car, but that still won't update the thumbnail or whatnot in the main garage menu.
To update the thumbnail, you actually need to go into the car's "tuning" menu. Upon exiting the tuning screen, the thumbnail will refresh with the correct PP.
I only noticed all this because I felt like many of my cars were way out of order, and upon looking into their stats and weight/power ratio, I noticed when I left the screen it would be correct.