How so?

The almost wholesale shift of obnoxious drivers moving from BMW M cars across to Audi's RS line after Top Gear started mocking the former and talking up the latter was a fast, pronounced change.

Apart from that, not sure. Top Gear was always pretty good when it came to car culture, it's just a lot of surface level "car fans" just follow their word and end up being the face of the trend.

Where I live we have countless boy racers with farty exhausts obnoxiously informing everyone at all hours of their amazingly unique and original ideas about how to modify cars. I pin the blame in no small part on Top Gear for spreading a dumbed down car culture to the masses. That's not to say I didn't enjoy watching it. I just don't enjoy what it contributed to bringing about.

That's nothing to do with TG. They've been doing that for decades. Top Gear's mods were stupid, and no teenager uses it as the motivation for modding their car.

If anything, they get their inspiration from across the pond. TG is an older man's comedy show.