If you were around in the 90s, you remember Splitfire spark plugs- they were known for having a v-shaped electrode and claims of horsepower gains and fewer emissions.

One reader asks what ever happened to them and we have the full scoop here:

Ask the Editors: What Ever Happened to Splitfire Spark Plugs? - ATVConnection.com

 

I bought a car used once that had 8 Splitfire plugs in it. That was in the
early 90s and it was the first I saw of them.

Of course, there have been tons of automotive products sold with questionable
science behind them: remember STP oil treatment? How about Slick50?