F1: Closing the power gap in 2015 will be "very difficult," says Horner

Red Bull boss Christian Horner has admitted that Mercedes' rivals are going to have a 'very difficult' time closing the power deficit to Formula 1's champions in 2015.

With a big push being made by teams to relax F1's engine freeze rules, Horner believes the situation is still tough for Mercedes' opposition and particularly frustrating for his squad. Red Bull Racing, he feels, have faced numerous changes to aerodynamic rules over recent years that were aimed at holding back its dominant form.

"It's very difficult because with the chassis, if you're behind, you have the opportunity to develop," he said. "With the engine and this new technology, you're freezing immature technology and it's very difficult therefore for the manufacturers to recover.

"In the last few years there were regulation changes to try and slow us down, whether that was blown diffusers, double diffusers, flexible bodywork, engine mapping – the goal posts were always changing. With the engine, it's a frozen untouchable element so it's very difficult to reduce that gap to your opponents."

Despite his frustrations about recovering the gap to Mercedes and missing out on the World Championship titles, Horner believes RBR's 2014 campaign has been remarkable when put in the context of its disastrous pre-season test program.

"I actually think what the team has achieved this year is one of our biggest successes," explained Horner. "When you consider where we started, to be at this point in the season as the only team other than Mercedes to have won races, to be second in the constructors' championship and third in the drivers' championship…It's a remarkable comeback from practically no pre-season and obviously with the handicap of lack of horsepower that compared with the Mercedes-powered cars."