Esteban Gutierrez admits that it is too early to judge the full potential of F1 newcomer Haas' first car, but insists that he is already feeling at home in the VF-16.

The Mexican completed a productive couple of days behind the all-new US-based contender during the initial F1 pre-season test in Barcelona this week, adding a valuable race distance to the earlier mileage achieved by himself and team-mate Romain Grosjean in a promising debut for the first team to enter F1 since 2010's mass arrival that included what became the ill-fated Caterham and HRT teams, as well as the Virgin Racing that morphed into today's Manor operation.

Haas found itself able to lap on a par with expected midfield rivals and, although the inevitable teething troubles cost it track time over the four days, the to drivers logged 245 laps between them, creating a useful baseline for the second and final test, again at the Circuit de Catalunya, next week.

"I enjoyed driving [the car], so that's already a good start," Gutierrez reported, "Whether it's quick or not is yet to be seen, so it's a bit early to be speaking about performance or competitiveness, but both Romain and myself have the same comments, and that is a very good thing because we have solid feedback to develop the car on a direction and fine-tune it for the first race."

Gutierrez will return to the F1 grid for the first time in more than a year when he lines up alongside Grosjean for the team's debut in Melbourne, but is under no illusion that a tough road lies ahead of the squad as he makes the switch from Ferrari reserve to Haas racer.

"It is quite ambitious to say [we will be] 'at 100 per cent' [for Melbourne]," the Mexican admitted, despite the comparatively solid reliability enjoyed by the team in testing, "We have a lot of teams on the grid with so many years behind [them], so we can expect that to say '100 per cent' will take some time. I see that as our biggest challenge - to really get the team well integrated and working efficiently - but everybody has a great attitude, there is a great atmosphere here, a very good environment and, with that, I think we have a great base to follow through the next steps."

Testing resumes in Spain on Tuesday (1 March).