Formula 1 teams already well underway with their 2018 car development are facing yet another hurdle as McLaren blocked a motion that would see the retention of the 'shark fin' on the engine cover which returned this season.

The design had been outlawed in recent years but was not kept when the design rules changed for 2017. Initially, there were calls for the re-banning of the fin on aesthetic grounds but now the FIA wants to retain them so that teams can place either the driver's TLA (e.g RIC) or number on the side to aid spectators.

To achieve that, however, the governing body needed unanimous agreement from the teams which did not happen when McLaren vetoed the vote, meaning a compromise will be required to get the British team onboard.

Commenting on the team's position to not want the full fin to remain, Racing Director Eric Boullier admitted it was for competitive reasons but also promotional.

“Maybe we have found a way to use the engine cover that works better,” he was quoted by Motorsport.com. “The cars are complicated today so it is difficult for Zak [Brown, CEO] to find big stickers.

“We are not playing games, everyone is developing their own car so if you ask for something which is against our interests, I will not go for it.

“Some teams have tried to play something that was more suiting their car model, or whatever but we have a regulation in place for next year, so if there is no unanimity then there is no reason to change.”

The disagreement frustrated Force India COO Otmar Szafnauer as the Silverstone outfit already makes full use of the advertising space available on the engine cover thanks to their partnership with BWT and more.

“We have to release an engine cover soon, it would be nice to know the rules,” he said on Saturday. “I thought we had it all agreed.

“McLaren, I believe, wanted to expose the rear wing more, but the rear wing isn’t exposed only because it sits so low now. That is why you cannot see the sponsor. More so than because of the fin.

“The fin hides it from certain angles but not from head on – you can’t see the fin from head-on. You cannot see the rear wing because it is so low. For us, it removes a pretty big area for the sponsors.”