BUDAPEST, Hungary -- Red Bull team boss Christian Horner says Renault still has an estimated deficit of around 47bhp to Mercedes, but is confident the French manufacturer can close the gap.

Renault has struggled for performance since the introduction of new engine regulations in 2014, with a clear deficit in power to Mercedes for three seasons running. The French manufacturer made big steps forward over the winter and with an update at the Monaco Grand Prix, but Horner says the overall power deficit is still estimated to be as much as 35 kilowatts (roughly 47bhp).

"I think that Renault have made some great steps, we know that there's more in the pipeline and I think there's definitely more to come and it's how it works in harmony with the chassis," he said. "I think we know that we are 35 kilowatts behind, that's what the Renault guys tell us, and we know the plans they have in place to close that gap down."

Renault revealed in Hungary that it would not introduce any more Monaco-sized updates this year, but Horner says there is plenty more performance to be extracted from the current package.

"Well we have some fuel and some tuning and drivability that there is definitely performance to come from. We're quite confident that they'll still be some steps of performance by tidying up what we actually have."