The 'W-Duct' on Mercedes' W03 reportedly stalls the rear and front wing at high speeds, reducing drag. Getty Images
The Lotus Formula One team filed a protest at the Chinese Grand Prix on Thursday against the rear wing system used by rivals Mercedes.
The governing International Automobile Federation (FIA) issued a copy of a notice of protest signed by Alan Permane, the trackside operations director of the former Renault team, and handed to the clerk of the course.
The protest relates to the controversial rear wing which was declared legal for the first two races of the season and was passed again by scrutineers in Shanghai on Thursday.
Lotus believe the wing falls foul of article 3.15 of the technical regulations that says "any car system, device or procedure which uses driver movement as a means of altering the aerodynamic characteristics of the car is prohibited."
Mercedes, with seven times champion Michael Schumacher and fellow-German Nico Rosberg, scored just one point in the first two races but have sounded more confident about China.
The rear wing contains slots on the inside of the endplates that are revealed when the driver-activated drag reduction system (DRS) is used for overtaking, increasing aerodynamic downforce.
The open slots channel air through internal pipes to the front of the car.
"It's disappointing after three races we're still in this situation," Mercedes team principal Ross Brawn said of the protest.
"The system hasn't changed, the FIA's position hasn't changed, and as far as I understand their argument hasn't changed."
Champions Red Bull have also been unhappy about the wing, seeking clarity from the FIA on its legality before deciding whether to incorporate it in their own design.