Engine performance in Formula 1 appears to be rapidly converging.

When the new 'power unit' era began in 2014, Mercedes had a clear lead but Ferrari has been first to close that gap in the years since.

"I think our engine is as good as Mercedes," Speed Week quotes the Maranello team's chief Maurizio Arrivabene as saying. "In aerodynamics and tyre management we still lag behind."

Yet it is Red Bull that has actually slipped between Mercedes and Ferrari as the second fastest car in 2016, with the team powered by Tag-Heuer branded Renault engines.

"Renault has caught up," team boss Christian Horner is quoted as saying.

"And we know that there is more to come. We are currently about 35 kilowatts (47hp) behind - that's what the Renault guys tell us."

However, Red Bull will have to wait until 2017 for the rest of the gap to be bridged, with Renault's Remi Taffin announcing that the next big step will not be seen until next year.

"The big step will be next year's engine, race one," he said.

"Until we get to the end of this season we will be working on the specification we have now, trying to extract the most out it, but there won't be any more big steps as we had for races one and six."

Next up on the 2016 calendar is the German Grand Prix this weekend.