Audi refuses to confirm R18 spec details for Spa WEC race

The German manufacturer has confirmed that, as in the past, it will debut the low-downforce version of its current LMP1 turbodiesel hybrid at Spa next month, but it has declined to specify which cars - or how many - will run in this form.

A spokeswomen for Audi Sport told AUTOSPORT: "You will see at least one car in Le Mans specification at Spa, but we are not saying how many or which car number or numbers.

"You will find out at scrutineering on Wednesday [April 29]."

AUTOSPORT sources have revealed that Audi's full-season WEC entries [pictured] will run in a configuration optimised for the Spa circuit, whereas the additional, third entry will run closer to full Le Mans specification.

That doesn't necessarily mean that Audi is exactly following the route taken in each of the past two seasons when the extra car for Spa and Le Mans has run in low-downforce trim and the two regular WEC entries in high-downforce spec.

The low-downforce versions of the two previous iterations of the R18 were distinguished by a longer tail section that extended under the rear wing to the full length of the car.

New rules for 2015 mandate that the rear crash structure must be covered by bodywork, meaning that the tail of the high-downforce car that won the WEC opener at Silverstone earlier this month already runs to the rear extremity.

The low-downforce R18 undertook a four-day test at Paul Ricard last week, which included a 30-hour Le Mans simulation.

The third Audi for Spa and Le Mans this year is driven by Audi GT star Rene Rast, who has been promoted to the LMP1 ranks for the two races, and prototype regulars Marco Bonanomi and Filipe Albuquerque.