Yes we bought one and tested it and found their claims to be wrong. We also noticed that their claims that you can use it with other fueling boxes is not quite correct either. We noticed that if used with a fueling box, the power will drop. We also saw 1. 5-2mpg fuel savings but after driving with it for 3 weeks the mileage gain droped back to what we were getting originally. We contacted them to take them up on their return policy but they would not take it back. They also would not talk to us any more. Ours went to the garbage can. Too good to be true usually is too good to be true.