Lewis Hamilton thinks Honda is now just 10hp behind the top engines in F1.
The Japanese manufacturer struggled when it returned to the sport in 2015-2017 with McLaren.
But now with Red Bull and Toro Rosso, Honda is thriving.
"Without a doubt, Red Bull has a much better power unit than a year ago," Mercedes' reigning world champion Hamilton said in Bahrain.
"I think in terms of performance, Honda is very close to the best engines," he added. "I would say it's about 10hp.
"When we look at the GPS data, we can see they are as fast as we are," said Hamilton.
"I hope they've gained in terms of reliability too."
