Haas development driver Santino Ferrucci says F1's new spec cars are a bit of a handful when driven on the limit.
The 19-year-old American junior, who just stepped up from GP3 to F2 with Trident, was behind the wheel of Haas' VF-17 car in last week's in-season test in Budapest.
Ferrucci acquitted himself well, keeping himself out of trouble but admitted to have been a bit overwhelmed by the sheer power and speed of F1's latest generation of cars.
"Everything is a massive step, GP3 to F2 was huge," said Ferrucci.
"On carbon brakes [in F2], my first push lap out I broke 30 metres too early, looked up, was at the 50 and had to get back on the gas.
"It was an experience, to get in [the F1] car, I was just getting used to the brakes in F2, in F1 the braking point is roughly the same, it wasn't that big a step.
"What's more of a step is the high speed, the F1 car is just nothing like anything [else]," he added.
Ferrucci described his experience of getting to grips with the Haas VF-17 and remaining away from the ragged edge.
"With low-speed and mid-speed I'm pretty sure I'm really on the limit, or within a km/h or two," he said.
"In the high speed, obviously every lap I go through it's like half a km/h more, half a km/h more. The problem is though, when you find that limit, when you lose the car, you just kind of hit the brakes and hold on and try and keep it out of the way.
"This car on the limit, it can be a bit scary at times, so in the high-speed I prefer to just back off a few km/h and lose a tenth and be safe rather than risk it every lap."