McLaren become first team to take advantage of the final green-light for double-decker diffusers in Formula 1 by fitting an interim version to its car in Shanghai already. The change for China is far from being a full double-decker design, which is expected to appear in subsequent races and is more akin to Toyota's narrow diffuser extension. This change is a small improvement over the version run in the last two races, but scope still exists for a full double-decker conversion soon.
Full conversion need changes to other parts such as the rear crash structure and rear suspension, as well as the aerodynamic parts upstream of the diffuser such as the front wing and bargeboards.
Other teams have been developing these diffusers in expectation of the FIA court of appeal ruling with Renault possibly introducing its version of a double-decker diffuser this weekend.
Most teams are expected to fit the design by the Spanish Grand Prix, although Red Bull Racing may have to wait until as late as either the Monaco or Turkish race before its version is ready.