Fair enough, that's part of how they advertise it...but I'm going to take a chapter out of Dave's Technobabble a couple of months ago. Somebody was asking about a similar device in the path of the exhaust to encourage a 'vortex' flow pattern, in hopes that this would increase the velocity of the gas passing through the pipe. Same concept as the tornado.
Dave basically had this to say -
A 'vortex generating device', even if it did produce the desired flow pattern, would be more of an obstruction than an aid. He mentioned that the exhaust flow is not consistent but travels in pulses, especailly further upstream. The same is true for your intake tract, where the throttle plate is constantly controlling flow. Every time flow slows the 'turbine/pinwheel' spins down, but when it is supposed to speed up again the air must first spin up the turbine before it can pass through at the desired speed.
Also, there are no advantages to producing a vortex in your intake or exhaust pipe; the gas will not travel faster along the axis of the pipe, but rather use its energy to complete the vortex pattern, travelling much farther than it needs to go.
What you may be thinking of when you think of a vortex as increasing flow is the bottle-to-bottle water tornado trick.
You see the fluid drain much faster when trapped in a vortex and think the vortex helps the fluid move...in reality the only reason it flows better is that the top bottle needs to be refilled with air at the same rate that the fluid travels out so the vortex, by forcing fluid to the outsides of the container, allows air to pass through the center and voila.
In a flow situation where there is only one fluid or gas traveling in one direction the optimal velocity is achieved by giving it the most direct, unobstructed path possible.
Now if in fact you do see an increase in gas mileage my suspicion would be that the tornado reduced intake flow enough for the ECU to reduce the pulse to the injectors to keep the A/F right. And in that case you're just increasing your gas mileage by reducing your horsepower.
And as my good friend Joe G says about cars like the Echo:
Yeah, I'd get 45 miles per gallon too if i took 10 seconds to go from 0-60
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