Engine is Red Bull's question mark - Ricciardo

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Daniel Ricciardo says the performance of the Renault engine will be the decisive factor in whether Red Bull is competitive or not in 2016.

Red Bull had a difficult start to 2015 as it struggled to get the most out of its chassis and Renault worked on reliability issues. The power unit remained a weakness for the full season, though the team managed to improve the car's performance dramatically to finish with both drivers on the podium in Hungary and challenge for victory in Singapore.

With Red Bull continuing to use Renault power units - albeit badged as Tag Heuer - in 2016, Ricciardo says the team knows it can produce a car capable of fighting at the front but is left waiting to see how strong the engine will be.

"I'm not going to go in thinking we can win the title. That would be the wrong thing to do," Ricciardo told Autosport. "If it works, awesome. I think we've got the platform.

"The way the team developed the car last year, it's really proven not only the quality of people, but the motivation and the hunger still within the team. That's been the most promising thing: I haven't seen any doubters or anybody lose motivation. Everyone's still as hungry as ever.

"Unfortunately now it's probably always going to be dependent on which engine we have and that's going to dictate the success a little bit. But mechanically we can definitely build a good car for 2016. How good is the engine going to be? That's the question."

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