AMSOIL P.i. - A Study in Performance - In response to Environmental Protection Agency (EPA) fuel economy and emissions regulations, fuel injection systems replaced carburetors in new vehicles in the 1980s. Fuel injectors allow more precise control of fuel than carburetors, improving fuel efficiency and minimizing emissions. However, in order to work efficiently, they must be kept clean. See how Amsoil's Performance Improver made out.