I've been playing iGP since 2020 and I have a question regarding design points. I know that the car distribution points are reset from one season to the next, but for example: If there are 3 races left in my current season, if I don't distribute the design points per race until the end of this season, do these points accumulate and can I use them for good next season?
No. Any DP that aren't spent for the final race of the season are lost.
You always start a new season with 0 DP and your design reset according to the strength and weakness of your CD(s).