Cruise.
Reach max speed.
Press Z to engine kill.
Tap X for reverse once.
Power starts to regenerate.
You're now at 280-340 ish speed generating your power core.
@NoMe hey man, i never got it to work either up untill today. It takes a little bit for it to start recharging but it does work. You press strafe for like 00.00.13 seconds then it should recharge