This season could end in controversy as Mercedes has written to the FIA seeking clarification over the wind tunnel rules in light of Ferrari's relationship with Haas.
Haas are set to enter Formula 1 next season running Ferrari engines and other parts.
As such rivals fear that the Scuderia have been using Haas' wind tunnel time to develop their own package.
Earlier this year these fears resulted in an FIA investigation as wind tunnel use is limited under the current regulations.
Ferrar were cleared of any wrongdoing.
The matter is now again on the table after Mercedes wrote to the FIA requesting clarification regarding the rules governing wind tunnel usage.
The World Champions, though, deny it has anything specifically do with Ferrari and Haas.
"It is just a clarficiation and is not aimed at any team," motorsport boss Toto Wolff told Motorsport.com.
"We have been seeking some answers which were not given in complete clarity from the FIA before, and I think this is for everyone to know what the situation is."