Users can experiment with their placement for optimum performance?? That's laughable!!! Unless they're testing it in a wind tunnel or other controlled environment, users won't have a clue whether one configuration is better than another. And why on earth have they placed them in front of the windshield? The point is to generate a vortex to help the air flow cleanly. Used in this way, the air will hit the windshield and immediately lose any benefitial effect of the pods.
Furthermore, I'd be very surprised if the fuel savings generated by the aerodynamic gains made by such a device would ever surpass the initial cost. This type of device serves a function on something like a Mitsubishi Evo, directing the airflow more effectively onto the rear wing, but on your average family car I have strong doubts as to their usefulness.
This type of device belongs on ricer cars, just behind the painted black hood.

Attached with padded rare earth magnets? Seems like an opportunity to get a free collection of these things to, well, I've no idea exactly what, but I'll start with the fridge. An aerodynamically justifiable fridge, ..at last.
Tests in windtunnels have shown... ...typically the model used in windtunnels studies is laminar airflow. In such a steady state you can introduce vortex generators and work out their effect on the flow. But, when you realise that common cars move almost all of their time in turbulent air, these things really make no sense.

Looking forward to beating up the first schlock who's car hurls one of these into my windshield. And while I'm at it, I'll stuff him with all the other gimmicks that I'm sure he will have pimped his car with: some "magic gas saving additives", a "hydrogen generator", the inevitable gas-mizer aftermarket computerthing, and every book on the topic I will surely find on his passenger seat. And then I'll show him how to ride a bike.

VERY funny BeWalt! You know in my case by keeping my tires properly inflated, using synthetic oil, and the magnets on my fuel lines I get such good mileage I have to take some out every now and then? :-P

To me it looks like they are trying to use turbulators on a car. Turbulators work quite differently than vortex generators as the latter are placed on the leading edge and turbulators on the trailing edge. The laminar flow around a car is quite limited though so I suppose these would work less good than turbulator tape on a glider wing but it might actually work if it reduces backdrag. I have a friend that commutes 140km a day on a freeway and has a neat diagram over her l/100km consumption. I suppose she would be able to notice a 3, 4 or 5% difference and easily could figure out the best placement of these bumps on her car.

This needs to be adapted for Commercial trucking. In a business where saving one penny per mile can amount to millions of dollars, this has vast potential.
The other advantage is that there's only one basic model for the back end of a trailer.

I have been using "fuel fins" for the past few years which are similar to gas pods. I have placed farthings over the back tire area, partial farthings over the front (only about 2" wide or the tires will touch when turning), farthings on the sides between the tires (about 4" wide tapered near the tires which can touch when going over a hump if the car goes fast), a covering over the bottom part of the front windshield, a horizontal "V" shaped plastic in the front of the car to cut the air and I have drilled numerous holes in the back bumper to allow the air to pass through to prevent suction. My car is a 2003 Toyota Echo and I get about 50 mpg at 50-50 mph. If I lower my speed to about 45 mph, then my mpg increases. I made my farthings and "V" front bumper out of the sides of plastic containers. I placed the "fuel fins" on the top, sides and back trunk below the rear glass of the car.

I have seen similar little gizmos stuck on the back of small Japanese made hatchbacks... The only function claimed by one of the guys was that they covered up the original mounting holes for the stock rear spoiler that had been replaced with a more stylish JDM aftermarket spoiler.... A set of Moon Disk wheel covers or a Beatrush under panel would be more effective in reducing wind drag...

I see few places these will improve aero and almost all others it hurts aero. They are too thick, thus increase frontal area. One needs more, smaller ones to work best with the least drag.
One might use small toy magnetic checkers as well as these overpriced nubs and probably get a better result. Also a tape line kinda like a spoiler flap with the center stuck to itself and the edges on the car, with the flap going up to trip the airflow.

Works best when used together with magnetic bracelets and frequency therapy devices.