Sebastian Vettel made his feelings about modern-day Formula One clear after his car ground to a halt midway through the Russian Grand Prix.

The four-time world champion, whose Ferrari had suffered a failure of the complex MGU-K system, opened his radio channel to say simply: "Bring back the f---ing V12s!"

It was a dig at the six-cylinder V6 turbo engines F1 has had since 2014. Vettel has been an outspoken critic of them from the beginning -- early on in that debut season, he said the muffled sound of the hybrid units was "shit". Before then, Vettel had driven the louder V8 engines since his F1 debut -- those had replaced V10s in 2006. V12s were last a feature of F1 cars in the 1990s.

Speaking after the race in a Ferrari press session which centred mainly around his reluctance to follow a team order early in the race, and the team's reaction to that, Vettel said his comment came from the bitterness of retiring from such a strong race position.

"Obviously there is no option [to go back]," Vettel said after the race. "These power units are very complex from an engineering point of view very fascinating, but obviously I have my stand on it," Vettel said. "I don't think it comes with a great upside for us racing and people watching.

"In that moment, obviously it was very bitter, because up to that point I thought I drove very well and it was looking like a good afternoon. The first reaction when the car breaks down is not always the happiest one."

Sebastian Vettel hasn't out-qualified Charles Leclerc in nine races. Mark Thompson/Getty Images

Vettel is far from the only person lacking affection for the V6 engines. Reigning world champion Lewis Hamilton has repeatedly stated his wish for F1 to go back to a previously-used engine -- speaking in 2016, Hamilton named a V12 engine in his ideal scenario for an F1 car.

The hybrid power units feature complicated technology and despite achieving some remarkable things - power output matches the normally-aspirated V10 era, albeit using half the fuel -- this era has featured engine penalties becoming a regular features of races in the latter stages of the season, with each driver limited to a certain number of each of the components which makes up the whole package. Teams are also critical of the high costs associated with the V6s.

Changing the current engine formula is not an option in the discussions between Formula One and its 10 teams about the extensive rule changes planned for 2021. FIA president Jean Todt has previously said a move back to some of the louder engines of F1's past "would not be accepted by society".