When a vehicle is coasting in gear, combustion doesn't take place inside the internal combustion engine. The wheels drive the engine through the transmission.
Overspeeding has negative safety and economic effects. Also, in trying to beat time by speeding excessively, the driver might end up having more travel time.
Best way to react when bonnet flies open when driving is to think fast, watch around within split seconds & brake. There are things to do to prevent occurrence.
Where there is no way to fix an overheating car on the spot, these are information needed to be able to drive an overheating car to a workshop or safe place.