Despite setting the pace at Valencia on Wednesday, Fernando Alonso is refusing to pass judgement on his F150's pace.

The double World Champ was in action for the second successive day, putting the mileage on his new Ferrari F150.

With aerodynamics and a comparison test between the various Pirelli compounds on the agenda, Alonso put in 108 laps of the Spanish circuit with a best time of 1:13.307.

Alonso's time meant he finished P1, 0.307s up on reigning World Champion Sebastian Vettel. It was also fastest time of the week to date.

But despite his flying pace, the Ferrari driver insists he's not yet in a position to pass judgement on his new car.

"At this stage it's difficult to feel the competitiveness of the car, because in the past there were lower fuel loads, so it was easier to compare, with the tyres," Alonso said.

"Now also you have no focus (to compare) - normally your team-mate was with you in the (tests).

"I feel good. I remember starting with a new car, a three-lap run, then a six-lap run, then a 10-lap run.

"Slowly you build up the runs, you check the temperatures and everything."

The day's action at Valencia was another opportunity for Alonso to familiarise himself with this year's new regulations, including the moveable rear wing which is activated by the drivers.

"It was a good start for us. Today we did more than 100 laps, which was the priority - to do a lot of kilometres.

"The moveable rear wing has been a new device for us so we are making use of the system. It's not so easy to activate and de-activate before the corner, so there is some time of practice before we get used to it.

"And again the same with the KERS. So these extra buttons on the steering wheel require some time.

"I had some time in the simulator and now this time today, so I can say I am quite happy with everything in the steering wheel. It has been a very productive day for us."