It can't work, if it does then there was an unrelated problem with the engine and MPG that was fixed when this was done.
The problem with most of these types of "items" is that they try to evade the the laws of physics while using "simple science" to make their product make sense to a potential buyer.
In the "good old" carb days some changes to air flow and fuel dispersion could get you better MPG, but since they added fuel injection and computers to monitor combustion efficiency these products won't help and in fact can hurt MPG and power.
Air turbulence for mixing fuel and air isn't always a good thing, porting and polishing intake, heads and exhaust speak for themselves but that is for power not MPG, and anytime you go after power you will lower MPG each time you use that power, laws of physics.
Increasing the air turbulence in the intake will lower power, and so increase MPG, but it isn't a fair trade off, you will notice the lack of power well before you see any MPG increase.
If you just keep your foot off the gas pedal and drive less aggressively you will get the better MPG and still have the power if/when you need it
Vaporizing fuel is a popular scam, air/fuel mix of 14.7:1 is best MPG you can get, this is by Weight, so 14.7lbs of air to 1lb of gasoline.
14.7 parts air and 1 part gasoline, doesn't matter if gas is a vapor or a spray, it still needs to be 14.7:1
They sell these devices with simple science making people think of Volume, a vapor will use less gasoline by volume, but it doesn't, it just takes more Volume of vapor to achieve the 14.7:1, laws of physics again.
Computer tries to keep unburned fuel in the exhaust to a minimum, so tries to maintain the 14.7:1, which is the best MPG point for your vehicle, I think target is closer to 14.2:1 because slightly rich gives a better balance of power and keeps cylinder temps lower.
If you try to run an engine leaner say at 16:1, then engine cylinder will overheat and pistons and valves will melt, but you would have better MPG until that happened
maybe 3 or 4 minutes
Fuel injection has increased MPG, sequential injection even more, lighter engines and vehicles also increases MPG