1.
In a vehicle such as a car or a bus, the driving seat is the seat where the person who is driving the vehicle sits.
He got into the driving seat and started the engine.
= driver’s seat
N-SING : usu the N
2.
If you say that someone is in the driving seat , you mean that they are in control in a situation.
At 69 he is as firmly in the driving seat of the company as ever.
PHRASE : usu v-link PHR , PHR after v