Jerez F1 test: Felipe Nasr thinks Mercedes runners hiding true pace

The Brazilian ended his first test with the Hinwil-based F1 team two tenths faster than Ferrari's Kimi Raikkonen, and four tenths quicker than Nico Rosberg's Mercedes.

Nasr set his fastest time during a run on soft Pirelli tyres in the afternoon, while both Raikkonen and Rosberg did their fastest times on mediums.

Felipe Massa's Mercedes-powered Williams used soft tyres to go seven tenths slower than Nasr's Sauber, but Nasr told reporters after the test that he felt the Mercedes runners could have gone much faster if they wanted to.

"I think maybe the Mercedes cars are hiding a little bit what they can do," he said.

"I didn't see them running what they could do 100 per cent.

"You never know, it's testing. We don't know what programmes the others are doing. I'm just happy we did ours."

When asked whether he had completed his own fastest run on low fuel, Nasr replied: "I wouldn't say it was maximum performance, but they were decent runs on the soft tyres.

"I think we could still get some margin on the car to improve that [the laptime], but in general it was good.

"To be honest, I don't feel we're going to be leading sessions in this car in other situations, but nevertheless it feels good to finish first."

EARLY SPIN

Nasr suffered a spin at the fast Turn 9 early in the session while the track was still damp.

He said he was trying to learn the correct conditions to switch from intermediate to dry tyres.

"I think I was the only one to drive on dry tyres at that time," he explained.

"It was purely for myself to get to know how much crossover you need to go to the slick tyres.

"It's something I have to try now - I don't want to do it [for the first time] in a race.

"These things happen. At the exit there was a wet patch, and as soon as I touched it I just went off. It was nothing major."

Nasr will now hand the C34 back over to ex-Caterham racer Marcus Ericsson for the final day of the Jerez test on Wednesday.