F1 testing: Williams to let Felipe Massa try radical rear wing

The double-decker device was trialed by Williams as it seeks to find the optimum balance of this year's car, as well as potentially simulate downforce levels for 2017 when new bodywork rules come into force.

Development driver Alex Lynn, who finished ninth quickest of the 10 drivers in action, said: "I didn't push that hard on it, I wasn't allowed to.

"The only laps I pushed were the end of the morning on the medium tyre, so it was about getting aero scans for it and straightline speed stuff.

"It was a bit of a shame as it looked like it would have given some good downforce, but I wasn't quite able to do anything on it.

"You'll probably see Felipe do a bit more on it tomorrow. He'll be the better one to ask."

Lynn suggested the look of the wing was "old school", adding that "it reminded me of that Senna Toleman at Monaco, one wing in front of the other".

Lynn, who won the GP2 sprint race in Spain on Sunday with new team DAMS, was pleased with his overall return to the cockpit of an F1 car.

The 22-year-old, who also drove for Williams in the corresponding test at the Catalunya circuit last year, said: "It's really nice driving an F1 car. It doesn't get much better than that.

"To get so many laps [86] is really important for me in my development. So yeah, I'm really happy.

"I felt it was a lot easier than the last time I drove. Maybe it's just another year's experience of driving higher-powered cars, but it felt much easier."