Honda is "clearly" making progress with its Formula 1 engine, according to McLaren team boss Eric Boullier.
The first year of the Anglo-Japanese collaboration in 2015 was disastrous, but Frenchman Boullier says that Fernando Alonso's Q3 breakthrough in Spain was significant.
"By studying the data closely, we see that we are now somewhere between Mercedes and Ferrari with the power," he told Speed Week.
"Progress is clearly felt by the drivers and also on the track everyone can see that we have become stronger. So we are on the right track."
Some of that progress may have been made through a tweak to the Honda 'philosophy', where until now the manufacturer has often appeared content to take its time in pushing towards the front.
"Yes and no," Boullier said. "Honda has always had a good approach and is prepared to respond quickly. You can feel that everyone is working at full throttle.
"And the changes that were promised are coming. Honda president and CEO Takahiro Hachigo will be in Monaco."
McLaren does, however, appear unlikely to give in to mounting pressure - even from Honda - to allow the Japanese engines to be supplied to a customer team.
"It is important that no team will be left without engines," said Boullier, referring to the tweaked rules for 2017 and beyond.
"But in my opinion, there is no reason to say that Honda is able to supply engines to Sauber or Toro Rosso next year, although there is talk of that in the press. It will not happen."
The season continues on May 29 with the Monaco Grand Prix.
