Notice they dont have pics? Because its a 5 cent resistor, its a scam, one of the oldest in the book. Save your money, inflate your tires to sidewall max and read through the hypermiling tips on the top right of the site.
Yup, just a resistor. I did one from e-bay for $6 total for fun to find out what resistor they were using. It was the cheapest I could find that still satisfied my curiosity.