The team rented a workshop in Austin leading up to the event to modify its VF-23s to become the final team to converge around the downwash sidepod concept pioneered by Red Bull.
Haas debuted new sidepod inlets, engine cover bodywork and floor for its home race in a bid to address the major in-race tyre wear issue caused by an aerodynamic imbalance.
But the verdict from drivers Kevin Magnussen and Nico Hulkenberg following the Saturday sprint race at the Circuit of the Americas was that progress was not immediately obvious.
Magnussen, who finished 18th following a scrappy battle with Zhou Guanyu, said: “It didn't look too good, honestly. But we'll investigate and see what we think.
“It's just frustrating. [The tyre struggles] looked a little bit similar… It wasn’t a great sprint.
“The pace dropped off a lot… I got a decent start and a decent first lap, then stayed there for a few laps before the well-known cycle of getting overtaken and the tyres dropping off started.”
Team-mate Hulkenberg climbed a place to 15th, but only after Aston Martin driver Lance Stroll was forced to retire with brake failure.
The German reckoned the team had been limited by the sprint race format, which only leaves one 60-minute practice session before two qualifying shootouts.
Accordingly, Haas will start both cars from the pitlane - as will Aston Martin amid similar upgrade and set-up headaches - so that it can break parc ferme regulations and overhaul the rear wing specification.
Hulkenberg said: “First glimpse, obviously not a transformation unfortunately. But it feels like it was the first real session, with this car, with this package.
“FP1 is obviously very compact, very condensed, a lot of things going on, different tyres, different fuel loads, etc, etc, and two times quali so it was hardly any running.
“There's more to explore, more to unlock, probably also to readjust the set-up around it a bit more.
“But we need time and track time and we didn't quite have that yet. But it was expected to be tricky to bring an update of that magnitude and hit it on the head the first time.”
Specifically addressing the exaggerated tyre degradation, he added: “It wasn't like I was catching people at the end. So, I think deg was the same or maybe worse than others.”
Meanwhile, team boss Guenther Steiner said: “We’ve got more work to do but initially we’re not very happy with what’s happened… We found a few things and went in the wrong direction.
“But it’s difficult to jump to a conclusion after one practice, two qualifying sessions and one short race. “But at the moment, we have to find more as the upgrade’s not done what we expected.”
