You all know that now no one is investing in the cooling and reliability of the car.
I suggest to introduce a limit on the number of engines that can be used during the season at the level of the league rules. For example, you can use only 5 engines for 20 races.
With parts, everything looks more complicated, because at each level their number is required differently, but it is possible, for example, in leagues with a rule for limiting parts, to develop another system for producing them (as an option, by the number of stars of the manufacturing building) and another system for spending them on repairs (so that it does not depend on the level of the player). And then, of course, all the parts left over from previous seasons should be banned.
For violations of the limit, of course, it is necessary to give disqualifications from races in which this limit was violated.
I think these innovations could diversify the gameplay.