Solved

Design Limits = 100??

Please could you let me know if the design for each attribute of the car is capped at 100?

By that I mean, thanks to my Chief Designer my Acceleration is +2. I have developed it up to 98 and so effectively it is now 100. Do I get any extra performance by developing Acceleration by another 2 points (effectively 102) or does it make no difference because performance is capped at a 100 value and I should therefore spend my points elsewhere?

I was wondering the same, would be nice to have an official answer.

100 is the highest
98 for +2
99 for +1
Research does not show the pluses leaving your name out of best team category even though you have 100 overall. But this is ok because the name not on the list means you are getting better bonus points on other things.

I have assumed the cap is 100. Any bonuses I have stop development at 99 because they are 100 after the bonus. The extra design point saved is re-distributed to another design attribute.

The confusion is directly coming from the review feature (in cars tab) and sometimes a "bad" performance when you are at 98% (+2) can make you doubt ..

Could just be that you had a bad day at the office, other thing is you can change one of the suppliers so you have +1 on 3 things instead of keeping the +2 later in the season.
Different suppliers where to work better at different tracks don't know if it was introduced or not, Ricky might could tell us.