For anyone confused about Overtake and Boost modes
Under normal circumstances, the new cars use a 50/50 split between the ICE (internal combustion engine), and the electric motor, which is power by an on-board battery and recharged by the MGU-K (Motor Generator Unit - Kinetic) to provide power.
When you hit a certain speed threshold (290 kph), regulations dictate that you must begin to taper off your battery usage until it hits 0, meaning you are now only using the ICE. Overtake mode increases that speed threshold substantially (337 kph), allowing for better acceleration and top speed for a longer period of time.
Overtake becomes available when you are within 1s of the car in front of you at the measurement point (apparently will be the final corner of the lap). It can then be used continuously, lap after lap, if you maintain that <1s gap (again, until you hit the now-increased speed threshold).
Boost mode dumps all of your battery in a very short amount of time and gives an incredible rate of acceleration. Boost mode can be used for both attack \*and\* defense. Boost mode can be used \*anywhere on the track\* #cars