Movies.

The car with the flames from the movie Grease?

I was watching Grease the other day and my Mother said that when she was in high school her boyfriend had a car that would have flames coming out of the back like in the movie. I was wondering how they did that and if it was dangerous. Thanks.

Put a spark plug in the tailpipe connected to a coil, burning too rich a mixture.
Harder to do now because of the electronic fuel metering, but possible.
Dangerous to whoever is in the flame path, when rolling ,not so much.

Greased Lightning