Gunther Steiner says his Haas team's 2019 Formula 1 car is the "strangest" machine he has ever worked with.
Haas continued to experiment with its car's aerodynamic specification during the German Grand Prix weekend and will again do so at this weekend's Hungarian Grand Prix.
Romain Grosjean has reverted to the team's Australian Grand Prix aero spec while team-mate Kevin Magnussen has run the latest package.
Steiner says his team is "baffled" by the VF-19 and that it cannot understand why the Haas machine's one-lap strength cannot be repeated in the race.
"We're still to understand where we are," said Steiner. "This is the strangest car ever I've worked with.
"I mean, you can qualify sixth - which in reality is eighth, I know that - or qualify fifth sometimes, and then in the race you just drop off to second-last. It's amazing.
"It hasn't been many times that a car like this was around. I don't remember anything like this, and therefore it's even more difficult. You cannot just go back and say 'hey, if you are always slow'.
"[In Germany], I think Kevin [Magnussen], without the lock-up, he would've made it into Q3 pretty easily. But then again, in the race, you end up being slow. I'm baffled."
Steiner added that Haas was continuing to analyse the data from running its cars in different specifications, but that mixed messages is making the choice of direction difficult.
"If we would've come to the conclusion that the Melbourne car is faster, we would change to the Melbourne car," he said.
"But we haven't come to that conclusion because in FP3, look at the time from Kevin, it was an amazing time. Where did it come from, I don't know."
Steiner has repeatedly suggested that the 2019 specification of Pirelli tyres is key to its fluctuating form.
"I think it's still the tyres," added Steiner. "It's how the car influences the tyre. When we get the tyre to work, we are on it - and we need just to understand that one, what does make it work and whatnot.
"We know the window of the tyre is small, where it works, and that will not change, so we need to find out why we are popping out sometimes and sometimes not."