Here are some ideas to spend surplus M$ when you get near your wallet cap of $5 million and there is no immediate requirement:
1. F1 2019 cars if you haven't already done so to reach invitational.
2 Maximize the two 2020 GT3 cars as they have exclusive series. Yes some gold is involved but both exclusives are fun and pay M$ bonus in addition to some minimal gold return. (monkey talk-A football stadium filled with Gold.)
3. Maximize the F1 2020 Belgian GP tuning pack-It's a decent tuning pack that can be applied to all owned f1 cars simultaneously.
4. GTE 2020- Install the LeMans 2020 GTE pack to the second car won in SE which has base PR (you can also install the same pack on the first car simultaneously). Then enhance this tuning pack by selecting the second car. This will earn TPXP for the second car and you can upgrade TP to increase the stats somewhat. You can choose to upgrade the TP on the first car too if you haven't already maximized, but once maximized enhance the tuning pack by selecting the other car or TPXP will be wasted.
5. FE 2020- As above, install the Berlin Pack on second car and enhance the Berlin Pack with second car selected to upgrade TP.
This is currently what I am thinking of. If you have any suggestions/thoughts, why not make it known so others may benefit?