The video is (Classic Car Challenge: Grosser Mercedes Vs Rolls-Royce Corniche | Top Gear) here, 6:30
Narrator (Clarkson): Mercifully the next test did involve our engines. Which car could achieve the highest top speed?
Clarkson: He's reached five.
May: Buffeting. I've got 80.
Clarkson: The radar trap was set.
May: 90. Good God, the trim's coming off.
Narrator (May): But with a six and three-quarter litre V8, the final result should be impressive. It wasn't.
Clarkson: Children come out of the womb faster than that!
Narrator (Clarkson): Before James had stopped I fired up the 6.3 litre big.
In this example "firing up" is before "stopping." -> I fired up the engine first, and he stopped after that.
Shouldn't the past perfect be used to refer to an action that happens before another action in the past?
Why is it "had stopped"?