Honda has queried whether Mercedes and Ferrari got complacent with the introduction of their updated engines at Spa.

While Alex Albon and Daniil Kvyat tested their new 'Spec 4' unit successfully, Mercedes had two failures for Sergio Perez and Robert Kubica while Ferrari also saw Antonio Giovinazzi pull off in qualifying.

In the case of Mercedes, such issues aren't new with Lance Stroll also losing an engine at its first race in Canada and seeing their rivals face setbacks shocked Honda.

“I’m surprised because of their reliability showed in the past, and also this year," F1 technical director Toyoharu Tanabe was quoted by PlanetF1.

"We can only use three engines per year, so they must run more than 5,000km. They have a lot of experience of how to guarantee the mileage and the reliability using dyno endurance tests.

“The new spec, of course, passed that durability test in the factory, then the engine came [to the track] and had trouble. That is one question and also [why I am] surprised.

“The other is quality control: they supply two or three teams for a long time, they know how to control the quality, how to check it before they ship [to races].”

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Explaining how Honda themselves had overcome similar issues last year with Toro Rosso, Tanabe wondered if perhaps some complacency had crept in.

“Your own team is important, so you can try something with the customer teams, how the new spec behaves at the track and then optimise the calibration and later you introduce the engine to your team," he said.

“Ferrari has a mature calibration or they know how to use the engine at the track efficiently, so immediately it performs well. That’s one of the ideas of using the customer teams.

“But at the same time, maybe you think ‘we are perfect, we can apply the engines [on all teams at the same time].”

Honda will continue with their introduction of the Spec 4 at Monza, having opted to spread the grid penalties over the first two races after the summer break.

This as Red Bull and Toro Rosso target stronger results at upcoming circuits like Singapore and Suzuka, which are more likely to suit their cars.

“From a PU point of view, the main development is that we plan to run the Spec 4 PU with all four drivers for the first time, after just [Alex] Albon and [Daniil] Kvyat ran it in Belgium,” Tanabe stated.

“For their first race with Spec 4, [Pierre] Gasly and [Max] Verstappen will therefore take grid penalties and start from the back of grid, but we believe they can still race strongly on Sunday."