Its a scam. A study showed that duct tape on the side of the car performs better.
http://wcpo.com/external/dwym/c3b519.html
http://autorepair.about.com/library/products/aafpr052002.htm
http://www.kirotv.com/consumer/2220354/detail.html
http://wcpo.com/external/dwym/c3b519.html
http://autorepair.about.com/library/products/aafpr052002.htm
http://www.kirotv.com/consumer/2220354/detail.html