Yep, it's true.  Amsoil is now offering a money-back guarantee on its top selling gasoline additive P.i. Performance Improver if the product fails to improve a vehicles mileage.  

Field tests show that Amsoil P.i. provides an average fuel economy improvement of 2.3 percent and up to 5.7 percent.  If a customer does not see a measurable fuel economy improvement in their vehicle after first-time use of the product, Amsoil will refund the purchase price of the product.

The P.i. money-back guarantee offer is good through December 31, 2008 and is open to everyone who drives a gasoline-powered vehicle.  Because the most dramatic fuel economy improvement is achieved after first-time use of P.i. in a vehicle with accumulated deposits, the money-back guarantee is limited to vehicles with a minimum of 25,000 miles that have not previously been treated with P.i. and have not undergone any fuel system or fuel injector cleaning procedure.  P.i. must be used with a full tank of gas, and P.i. treated gas must be run until the tank is near-empty before filling up again.  If customers don't see a fuel economy improvement  following use of the subsequent tank of gas after treatment then a refund is granted.  More info and qualification details are at www.amsoil.com.