Big oil _has_ political clout now but that doesn’t mean they aren’t aware that power can go away. The oil companies started funding climate change denial in the 1970s for that very reason.
There’s are interesting splits here, too: for the 20th century the interests of the oil and car companies overlapped but now they’ve diverged with EVs, and there’s even a market opportunity for EV makers to turn on their former partners trying to gain the environmentally conscious market. I think the fossil fuel industry leaders are keenly aware of those inflection points where partners will leave them.