Toro Rosso technical director James Key described the work done by Honda over the winter as "encouraging" after the junior Red Bull completed the most laps of any team during the first Formula 1 test.
Brendon Hartley and Pierre Gasly turned a combined 322 laps over the effectively three days of running after Wednesday was washed out, with the latter completing a single day best of 147 tours of the Circuit de Barcelona-Catalunya on Thursday.
It wasn't just the strong reliability either, with Key suggesting the performance figures from Honda mean they are now in a position to challenge the three manufacturers ahead of them.
"We had a good feel for where the Renault was last year and at least from the numbers you see, which you always have to treat carefully because they are from different dynos etcetera, it's not so far off," he told Sky Sports.
"Not nearly as far as was being suggested last year actually. It was probably pretty close to Renault towards the end of the season and obviously they've made steps for this year and that's encouraging."
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The respected British designer does admit their new Japanese partner is not quite on the same level yet as their former supplier, though doesn't think it will take too long.
"The good thing about what we saw from Honda last year is despite all the difficulties they had over the first half of the season they still had the capacity to go and develop the power unit and it definitely was better by the end of the year," Key stated.
"That trend appears to have continued into this year and, as long as that trend continues, there's no reason why they can't genuinely be challenging Renault by mid-season or the end of season. That's what we'd like."
Toro Rosso's showing in Barcelona has immediately drawn some to wonder if McLaren ditched Honda at just the wrong time, but Key believes the working relationship the Italian team has is much different and is working better.
"[We are] trying to give Honda the freedom they need," he said. "Fundamentally we wanted to give them the opportunity they needed to get on with the job. I think they appreciated that."
