Red Bull team boss Christian Horner has praised engine supplier Renault, as he believes the work they've done on their engine has helped his team to close in on Formula 1's current dominant force Mercedes.
Renault struggled with its engine in both 2014 and 2015, with it substantially down on power compared to the Ferrari and Mercedes units. That almost led to a divorce between Renault and Red Bull, before a last-minute deal was struck to continue the relationship, but rebranded under Tag Heuer.
Significant progress has been made on the engine side following a pre-season upgrade followed by a second overhaul in Monaco. Although Renault aren't planning any further changes until 2017, Horner believes the work that has been done at Renault's Viry facility has helped to halve the gap between Red Bull and Mercedes.
"The most significant area is on the engine, and credit where's credit's due," Horner told Autosport.
"The guys [at Renault], with the restructuring they put into place at the back end of last year, the philosophy changes made, the developments brought in, the engine has clearly made a step forward.
"We've probably halved the gap to Mercedes, and there seems to be a real direction, and good leadership technically at Viry.
"We've made progress on the chassis, and of course these things have to work in combination, but the biggest element I would say is the step forward in the engine."
