However, Honda scored their best result since returning to F1 whilst in the back of the Toro Rosso, as Pierre Gasly secured P4 in Bahrain.
“Honda was a highlight for us. You remember what last year, at this stage, other teams said about Honda,” Tost said.
“I remember meeting some people here and they said ‘you must be totally crazy, we wish you all the best for next year’.
“I said ‘yes, we will have a good season, you will see, we will be in front of you’.
“They thought that maybe I am totally crazy, but I was convinced that Honda is the right decision to go with.”
According to Red Bull, Honda’s engine development took it ahead of Renault in the pecking order for the first time.
From next season and beyond, Red Bull will also take on the Honda power unit, like their junior team.
The Toro Rosso boss believes Honda’s gains in 2018 were real, but stressed than it started from a higher base than everyone expected.
“The Honda engine last year was already much better than other people said,” he added.
“During the winter months Honda and Toro Rosso worked really hard, we were at the dynos in Milton Keynes, we were at the dynos in Sakura.
“There was a very close cooperation, and Honda could improve reliability as well as the performance.”
Toro Rosso did go through more power units than any other team in 2018, but that was down to Honda testing the third specification of their engine in preparation for 2019.
“It was clear for me that during the season we will not finish the season with three engines,” Tost admitted.
“But the last changes of the engines was more or less the wish from our side.
“I see this season as a preparation for next year. This year is gone for us. Forget it.”