Red Bull Racing team principal Christian Horner felt frustrated by the false promises that Renault made regarding its power unit across the course of the 2015 season.
Relations between Red Bull and Renault soured dramatically last year as its power unit failed to match that of Mercedes and Ferrari, resigning Horner’s team to its worst season since 2008.
Red Bull did explore alternative power unit supplies with Ferrari, Mercedes, Honda and Volkswagen, but ultimately had to strike a deal to use rebranded Renault engines once again in 2016.
Horner opened up about the tension between Red Bull and Renault in an interview with Motorsport-Total, in which he revealed that the French manufacturer had promised to catch up with Mercedes in 2015.
“Mercedes has done a remarkable job with its powertrain, but in 2014, the days when they made mistakes, we were there to enjoy it,” Horner said.
“Ferrari and Renault were close enough to the level of performance that year. The problem we encountered in 2015 is that after our three victories in 2014, Renault had made us a promise that it would catch up with Mercedes.
“The expectations were very high on the side of Renault. When you’re an ambitious team like ours, we want to win, and if victory does not come, it’s frustrating. So it was frustrating because we had no control over the engine.
“We had a few problems on the car at the beginning of the year, but we could fix it. We had a good chassis.”