Stoneman says F1 car a big step up

The 20-year-old Briton earned the test chance by winning this year's F2 title, and had a full day of running at Yas Marina. He was entrusted with aerodynamic evaluation work initially, before being allowed to push for fast times in the afternoon, when he ended up fifth.

"We had a few new sets of tyres, but it's quite hard to push in an F1 car because there's so much aero on the car," Stoneman explained.

"It's knowing how much that will let you push and when it will bite. That was what I was doing throughout the day, pushing harder and seeing where the car was good and where it was bad. Towards the end of the day I was pushing more and more and seeing where I could make time up.

"Going from F2 to and F1 car is quite a big step. The difference between an F2 car and an F1 car is big with the aero."

Stoneman was pleased that the team had given him chance to settle in with the morning aero tests.

"It was a good way to come in and to approach the test day instead of going hard into testing," he said. "It was good to build up to the test and then in the afternoon go for a time."

He added that while he had settled in well during the day, he felt he would need several more sessions to really come to grips with the Williams.

"I'm used to the car now but to get that last five per cent out of the car you might need three or four days just to keep chipping away and fine-tune the car," said Stoneman.