First car I tried was the Elise (the one from the first tech preview - seemed to be the default), and I'd swear it has new sound samples because it sounds totally different, much more raw and throaty. That said, I've not driven it for several builds so perhaps it got a sound update earlier.
Not sure if they were always there and I'm just listening harder for new things, but I keep hearing the paddle shift noise, and it happens on the animation (which is late) rather than on the shift, so there is a mixed up order of sound where the engine note has already changed and then you hear the paddle click.
Tried some tyre lock ups, they seem to work as you'd expect, plenty of vibration through the FFB if you lock the fronts, and seems to have a greater effect on the softer slicks. No visual flat spot though.
458 GT2 seems way too easy to drive with TC off. Has some nice additional squeaks in its sound package.
LaFerrari is wonderful, some very interesting-feeling assists, and a totally different animal with it all switched off. Doesn't feel as heavy as I expected though.
Not driven the Formula Abarth for ages - feels like some nice improvements there, but could have happened a while ago. Used to feel like the tyres were skipping about too much when putting the power down after a bump, that's mostly gone.
The 12C still doesn't downshift properly.
T500 d-pad still doesn't work.
That's about all I've tested so far... off to Spa I go!