Toro Rosso's Brendon Hartley hailed the team's start to pre-season testing as "perfect" after running a trouble-free session, and completing the third highest number of laps behind only Red Bull and Renault.
Honda has not enjoyed the best reliability over the past three seasons with former partner McLaren and switched to Toro Rosso for the 2018 season.
The Japanese manufacturer's focus on reliability looks to have paid off though, with Hartley completing 93 laps as well as setting the eighth quickest time, albeit two seconds off Red Bull's Daniel Ricciardo.
Speaking after, the New Zealander described the day as a "perfect start" to testing for the team and Honda.
"We were first out on track and up until the rain hit and we boxed we’d done the most laps, we had no reliability issues and I think that’s the target for Honda, especially for this first part of the season.
"It was really positive today and the driveability was great, there’s really no complaints. A perfect start from that point of view and hopefully we can build on that."
Asked specifically about the driveability of the Honda power unit, Hartley added: "Very good. Actually the drivability is the best I’ve driven in the last two years in a Formula 1 car.
"It was really, really positive, all things directed towards Honda so that was really good. No complaints so far and we had a perfect day in terms of reliability."
Hartley is looking forward to four days of testing to best prepare him for the year ahead following his rushed introduction last year, when he was parachuted in for the final few races, but admitted the weather forecast could scupper those plans.
"I mean the tyre is a very tricky one in F1. Unlocking the tyre is one of the biggest challenges for the driver," he explained. "Getting it in the right window at the right time. That was something I struggled with a little bit early on last year and going in with almost no simulator practice, no real preparation at all.
"Unfortunately with the weather over the next two days we might not learn as much but I’m going to be much more prepared come Melbourne than what I was going into Austin last year."
