Honda's Yusuke Hasegawa is thrilled to see its latest power unit upgrade produce significant steps forward in terms of race pace as Fernando Alonso went from last to seventh place at Spa.

Despite being handed a raft of grid penalties for engine changes Alonso jumped from 22nd to fourth, benefitting from a timely safety car period and eventual red flag, but once the race restarted the Spanish driver profited from his higher position and battled consistently with the Force Indias while beating both Williams cars.

Hasegawa says the update was originally targeted for the Belgian Grand Prix with the aim to compensate for the lack of performance on the power-hungry circuits compared to its previous outings in Hungary and Germany.

"Obviously in Spa we thought we would have a very hard time and of course we are not satisfied with the current situation," Hasegawa said. "But we could almost achieve the same level as Hockenheim [in terms of competitiveness], which is very good. That is coming from the engine update."

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Hasegawa conceded Alonso's engine penalties may have been caused by the lack of preparation and testing on the new power unit parts but is confident with mileage under its belt the team can iron out its reliability issues to maintain consistent performances.

READ: Alonso: It was difficult to imagine going from last to 7th

While the engine penalty rules once again came under fire, with Alonso taking a 60-place grid penalty in Spa on a 22-car grid, Hasegawa isn't convinced of the cost-saving effects the rules imply by only using five power units per season and feels the biggest impact it has is needing to run a large mileage per engine compared to previous regulations.

"Obviously it is just very expensive, even with a limited number of engines, which means we need longer mile engines," he said. "We need more development for that and technically speaking, I don't deny longer mile engines. That is a good technical challenge. But it is not direct with the cost reduction."