F1: Ferrari fuel 'smells like grapefruit juice' - Christian Horner

New questions about the legality of Ferrari's 2019 engine are beginning to be asked.

In the winter test season, following a spate of FIA announcements clamping down even harder on the regulations, the general consensus was that the top engines in Formula 1 were now all close in performance.

But then came Bahrain, where rivals were shocked to discover that Ferrari's engine is five tenths better in a straight line.

One estimate puts the gap at 40 horsepower or 29kW.

"We actually thought that the FIA had filled all the last holes in the regulations," Red Bull's Adrian Newey told Auto Motor und Sport.

One new theory is that Ferrari's fuel sponsor Shell has discovered something revolutionarily new.

"The fuel from the Ferrari garage smells like grapefruit juice," Red Bull team boss Christian Horner said.