(based on the DS Techeetah Team)
The cheapest combination of Driver and Team Principal Levels to complete Formula E Season 6 (2019-20) is a Level 3 Driver and a Level 8 Team Principal, costing (63+111) 174 Gold.
You got (60+75) 135 Gold from v8.5 and v8.6 Special Events, so you need (174-135) 39 Gold to complete Season 6... AND you get 67 Gold back, so its Gold positive in 28 Gold.