Pierre Gasly has acknowledged that while Honda makes big gains with their engine, the time it takes to achieve them is often patchy.

The Frenchman will follow the Japanese manufacturer to Red Bull for 2019 with his season's worth of knowledge using their unit at Toro Rosso one area that could give him a slight advantage over new teammate Max Verstappen.

Certainly, despite Red Bull's persistent hype train of positivity, Gasly is well-placed to offer a more realistic assessment of the engine supplier's progress over the past 12 months.

“The development I would say is never consistent,” the 22-year-old told RaceFans. “Sometimes you don’t find anything for eight months and then suddenly they try something on the dyno that works and you get four-tenths suddenly. It’s not like a consistent development."

That's not to say Gasly doubts their potential to improve ahead of the upcoming season.

“Maybe mid-December they will find something that gives them five-tenths and will put us in a much better position. It’s too difficult they answer," he admits. "They clearly [have] not caught completely [Mercedes and Ferrar] but [they have] recovered a big part of the deficit.

“There is still one that I don’t expect them to recover straight at the beginning of next year but at some point, I know they are investing a lot and developing a lot.

“I expect them to get closer and closer but I don’t know when they will match them.”

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Gasly is also very aware of the eagerness of Honda to improve, reciting a moment with performance engineer Keisuke Minatoya after qualifying last year in Japan, which was Toro Rosso's best of the season.

“In Suzuka in qualifying we were seventh, but should have been P6 or P5. I was losing three-tenths in the straight and I came to see him afterwards.

“I was a bit disappointed even though it was a good result. [But] he was almost crying because he didn’t manage to give me the full potential of the engine.

“When you see the people you work with so involved in the performance that’s always great to see.”