Solved

Boosting 2 drivers same time

I watched 2 drivers ahead of me in a race, both were on the same team, and both were boosting at the same time. How is this possible?
Ps, I dont care that they beat me, my question is how did they do it?

Using button to the right of the battery you can "link" your drivers' batteries. Then clicking on battery activates it for both of drivers simultaneously.