The Hispania Racing Team (HRT) has threatened to lodge a protest against rival teams that run an off-throttle blown diffuser on their car if it is not declared illegal by the FIA in time for the Monaco Grand Prix. Speaking to Press Association Sport following the Spanish Grand Prix, HRT's team principal Colin Kolles stated that he had written to FIA president Jean Todt expressing his displeasure that the device had been declared legal by the governing body.
Prior to the Spanish Grand Prix, the FIA had announced that it was going to ban the use of the device that uses the flow of exhaust gases from an F1 car's engine to create downforce even when a driver's foot is not on the accelerator. The proposed ban never came into effect as the FIA could not agree upon an effective way to implement the ban. The ban could very well have lead to a shake up in F1's pecking order that is currently dominated by Red Bull Racing and Sebastian Vettel.
Kolles also claims to have the support of FIA's technical delegate Charlie Whiting on the matter. He argues that off-throttle blown diffusers fall under the category of moveable aerodynamic devices that have been banned in F1 since the end of the 1982 season since exhaust gases are generated due to the movement of valves and pistons of an engine.
The movement of the exhaust gases through the diffuser (which is fitted on the rear of a car) creates an area of low pressure under the car and literally sucks it to the surface of the road.