Been playing around with the Roadster MX5, come to the conclusion that the new tyre model has made it less realistic, there is also some bug going on. At Lime Rock i'm getting higher cornering speeds and higher speed on the straights than I was before (much higher, 5mph more in last corner for example) but my laptimes are actually slower than before.
Also the car has been turned into a knife on the fine edge tank slapper, its only a 170bhp car, it should be easy to drive, but unless you're a simracer that is used to driving difficult cars you will have issues getting it around a track, a real life race driver would need a lot of practice to get used to it, saving spins is a lot more difficult and almost feels like they moved the engine of the car to the rear when it starts to go ^^.
A few things the NTM does seems more realistic, but the driving experience as a whole is worse than before (on the Roadster), perhaps one day they will get it right, but not this time.
Cup car seems easier to drive, and doesnt have the speed bug that the roadster seems to have, the Cup Car is still very similar in the tankslapper aspect, just doesn't find itself falling into that situation so easily. You have to be smoother with driving them and much more careful how you distribute the weight.
It isnt all that much like driving a real car though, so a thumbs down from me on the Mx-5 side of things.