Romain Grosjean brought Lotus' opening winter test to an end on Friday and admitted he is expecting a stiff neck.

The Frenchman held on to his fastest time set by a 2012 car during the four days in Spain, although he was unable to match it on the final session.

'Everything is feeling good,' said Grosjean, who completed 95 laps on Friday. 'This morning we tried a number of different things on the car, including my first run on the soft tyre. In the afternoon we tried longer runs. Once it warmed up, the track temperature was hotter than yesterday, which helps our understanding of the E20 in different conditions.

'It's strange to think that we are already a third of the way through pre-season testing. We are pushing to get as much achieved as possible. I'm really enjoying being in the car even though it is hard work. So far my fitness has been good, my neck's not too bad, but we'll see how it feels tomorrow!

'I think everyone will benefit from next week away from the circuit so we can reflect on the data then go to Barcelona with some new parts for the car. I can't wait.'

Fernando Alonso picked up the fastest time of the final day in his Ferrari F2012, ahead of Jean-Eric Vergne's Toro Rosso, Sebastian Vettel and Lewis Hamilton.

Hethel-backed Lotus' team principal Eric Boullier added: 'This was a very positive test for us. Kimi R�ikk�nen and Romain both did great jobs in the car.

'The E20 has been reliable straight out of the box. We were not in Jerez to chase fast lap times, but of course it's always good to show strong pace.

'Of course, it is very early days; Melbourne is one month away and that is when we will see where we are. The E20 looks good out on track, it's a nice shape and it's very well finished which is a credit to everyone at Enstone.'