Look on the manufacturer's websites, and you will have loads of testimonials of satisfied customers.
People who spend hundreds of bucks on a product (at least what they cost down here) tend to become satisfied customers.
As I said in the thread that rugerman attached, the statements made by the salesman all appear mutually exclusive.
Also, if they worked as claimed, every car sold in the U.S., with their CAFE targets would be fitted with one.