1. Open wheel regulations. There’s a reason just about every plane covers or retracts their wheels. It’s a fucking dumb artifact of the 1955 F1 season.

2. 2-cycle engine prohibitions. With direct injection and MGU-H or sequential turbocharging clean burn/scavenging is possible.

3. Active aero / active suspension prohibitions.

4. CVT prohibition. I get this one the absolute least.