saw this on TV used on a dyno and supposedly it did a little better on mpg somehow, forgot if any HP gains. But last weekend messing around on the internet I found a place they sell them a *little* cheaper, especially is its a "pre-1980" car ($116?) so I order one up for my 1993 caprice work car.
Damn I get it in the mail and it's not like what they showed on TV. Must be the "pre-1980's " part. It's about eight little plastic open torpedos containing about 6 "gas pills" each- you dump them in your gas tank.

Wishing I woulda saved one and dissected it- smashed one "pill" and used the emissions spectrophotometer from work on it to see what metal it contained- probably just lead.

Remembring the "gas pills" from 1975 though and feeling just a tad ripped off for now though. Their influence on mpg is/would be so discreet just by measuring and driving a bit different your gas mileage goes up faintly.