Wider tracks would help, not easy to do perhaps.
All cars run the same Mercedes engine, its a great engine so lets do that, plenty of scope to choose drivers and aero and other enhancements to improve the car
Remove the tarmac run off and use gravel
Abuse the white line, like MotoGP you go through a penalty area which is a small diversion that costs you a few seconds. Its the only sport I know where the sideline is meaningless