Red Bull Racing's Pierre Gasly - with a year of Honda experience under his belt - says the Japanese manufacturer's claimed progress over the winter has been real.
The Red Bull camp ramped up at the start of the year its expectations regarding its new engine supplier, contending that Honda's power unit had made significant strides in the past months in terms of performance and reliability.
With regard to the latter, that assertion was supported by a trouble-free first week of pre-season testing in Barcelona.
But Gasly insisted that the engine's power had also improved relative to what was on offer last season when the Frenchman was racing with Toro Rosso.
"So far it's been really good, we haven't pushed it flat out but already you can feel the performance has increased," said Gasly.
"That's the main thing. And the reliability, we had no issue at all. Also, looking at Toro Rosso it looks really promising.
"Only good news from these four days. We need to keep working. The others are really fast, but at the moment we are testing a lot of things on our car.
"Now we need to understand what works best."
Red Bull was outperformed in the first four days of testing at the Circuit de Catalunya by its junior squad, with Alex Albon and Daniil Kvyat ending the week with the second and third fastest times.
©ToroRosso
But beyond a comparison of limited value, Toro Rosso confirmed the clear advance of Honda's development.
"Like every engine manufacturer Honda have been super busy over the winter, working on the next steps, and we’re carefully validating what they’ve learned over the winter," said technical director Jody Egginton.
“We’re introducing, step-by-step, these developments and pushing forward. Every team is nowhere near the edge of the operating window on the engine.
"Since this time last year the engine has taken a fantastic step forward. I
"It was clear towards the end of last year that they’d made that step and they’re just carrying on, so we’re very happy in that respect."
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