There was a TERRIFYING road safety advert that used to run on TV c.1975, in which real cars used to suddenly grow ferocious snarling faces and demonic eyes. Real-life footage was blended with cartoon imagery (in those days a fairly new technology) to achieve this effect.
It was designed to show children how dangerous apparently inocuous vehicles could be when they were moving and were stepped out in front of, but they had the effect of scaring the bejeezus out of a whole generation of kids. The camera would show a car heading towards the camera, and then this horrible roaring shark-toothed mouth would suddenly appear.
I hated them- my infants school decided to run the film over and over again to my class assembly during Road Safety Week, some of the girls were so frightened they were crying, and there were loads of complaints to the school afterwards.
The advert was pulled soon afterwards for similar reasons. Typical of the really stupid, crass insensitivity that so many people who did things aimed at children displayed at the time.
I was nervous of 1950s American cars for some time after that, as some of them (particularly the smaller ones) have fierce-looking grilles that reminded me of the advert.