The grip adjustments will indeed be interesting, they should better balance sports and slick tires for the race. Interesting dynamic with the slicks having quite an advantage in the first half... then becoming traffic for the sports tires later
You guys and your saving problems
frustrating to see as I know what it feels like. This will all be sorted out with the next big update. I NEVER had any "my car didn't save at all or got corrupted" issues with saving, so let me tell you what I usually do (or do not do):
When you want to work on a specific aspect of your car (engine only / trim only), use the hold/revert function. Stay within engine or trim respectively in that case. Press hold again to keep your changes and retest the car/engine to make it save.
When you want to make bigger changes to engine and trim, clone the trim and select the clone to work on.
Whenever you change your engine, go to the engine testing tab and run the engine test (you can abort it of course).
Whenever you change your trim, go to the final testing tab to run the car test.
Name your creations with simple unique names, using no special characters.
When switching to a different car to work on, restart the game first to be sure nothing gets fucked up.
Adhering to these, the worst thing I had happen to me in the many many hours of playing the bugged version is something not loading in quite right, fixing itself on the first car test. No disappearing or corrupted files.