It's atmospheric distortion plus some doppler effect, not digital; note telephoto lens indicating distance from the subject. Probably from a testing session. The other video has comparable trackside mics. The V8s exhaust freq was only about 20% less than the V10s, while the hybrid V6s was/is 60% less, which might make the V8 sound higher when juxtaposed. Was a bit off topic, I meant to post V8 sounds and they turned out to be comparison vids.