As an engineer I strongly object to such devices and companies who push
them. 

I looked at their web page. They are selling a "stationary vortex generator"
that makes the fuel charge burn better.

How do the vortices get past a mostly closed throttle plate?

How do the vortices get split up to go down the intake runners? Are there
just lots of them? 

Then after all that how do the vortexes get past the intake valves? Do they
just hang around and wait in line for the valve to open? Hey, the valves are
closed most of the time anyway. If strange vortexes hung around my intake
valves I would have them arrested for loitering.

Is the increased pumping loss caused by the added intake restriction (gotta
have a restriction since you put something in the intake path) off set by
the magic vortices increase in combustion efficiency?

Elvis didn't die he just went home.