 This loophole allegedly allows the U.S. auto industry to meet CAFE fuel economy targets not by developing more fuel-efficient models, but by spending between US$100 and US$200 extra per vehicle to produce a certain number of flex-fuel models, enabling them to continue selling less fuel-efficient vehicles such as SUVs, which netted higher profit margins than smaller, more fuel-efficient cars.In the United States, E85 FFVs are equipped with sensor that automatically detect the fuel mixture, signaling the ECU to tune spark timing and fuel injection so that fuel will burn cleanly in the vehicle's internal combustion engine.Originally, the sensors were mounted in the fuel line and exhaust system; more recent models do away with the fuel line sensor.