One analysis shows that while qualifying will be closer, the silver car may be a full second per lap faster than Red Bull in a race simulation or 'long run'.
Yet Finn Bottas insisted: "We are definitely not a second ahead of the others."
"We have the better chassis," he is quoted as saying by Auto Motor und Sport. "The difference is the engine."
Designer Adrian Newey thinks one of the big differences between Renault and Mercedes is how oil is consumed.
"For us, the oil consumption per 100 litres is 0.1 litres," he revealed. "Mercedes and Ferrari go the limit of 0.6 litres."
Ferrari, however, may be risking running out of oil altogether, as the plumes of smoke from the rear of the red car in Barcelona testing suggest.
Sebastian Vettel said that this is not a problem, but he did admit: "There are still some puzzles that we need to understand."
The Australian Grand Prix gets the new season underway on March 25.