The US EPA is required by Section 511 of the Motor Vehicle Information and Cost Savings Act to test many of these devices and to provide public reports on their efficacy; the agency finds most devices do not improve fuel economy to any measurable degree, unlike forced induction, water injection (engine), intercooling and other fuel economy devices which have been long proven. Tests by Popular Mechanics magazine also found unproven types of devices yield no measurable improvements in fuel consumption or power, and in some cases actually decrease both power and fuel economy.