Myself and a friend noticed last night it is not quite fixed.
In your garage your existing stock Riley will say P922, however when you go to use it, for example in Rivals. When you start on track, press pause and you will see your car now has a PI of P935. For some reason it has added the ‘weight reduction’ and it of course performs better.
To get it back to a proper P922 stock you have to take that car into ‘Upgrade Shop’ and restore it to default. Next time you load up Rivals and press pause you will now see it says P922.
A bit of a mess on, so you can also just sell your old stock P922 (which of course is really P935) and buy a new one and take that into Rivals and you will see when you pause the screen that it shows it as P922.
I thought I best mention this because if anyone out there goes to have a stock P922 race, then some of you may have an advantage running a P935 without knowing.