Romain Grosjean's first day in the Lotus E20 gave a further glimpse of its pace as the Frenchman led the 2012 field on day three of winter testing in Jerez.

Grosjean's best time of one minute 18.419 seconds was fastest around the Spanish circuit for a 2012 car since Tuesday, and took the Norfolk marque to almost one second ahead of Sebastian Vettel's RB8 and even further from Lewis Hamilton's McLaren MP4-27.

A Thursday tally of 117 laps was also good news for the Enstone-based Hethel-backed team, as all teams fight to find their early season reliability.

'I am one of the happiest guys in the world right now,' said Grosjean. 'It's been a really good day for me. We were fastest in the morning then we completed some longer runs in the afternoon. It's great to finally drive the car which I have seen coming together and being built at Enstone.

'The car feels good on the different fuel loads and tyre compounds we used. For sure there's margin for improvement in the tests ahead, but it's a great start to the year.'

Hingham-based Caterham handed new reserve driver Giedo van der Garde the CT01 reins on Thursday and the Dutchman clocked 74 laps that peaked with a 1:23.324 – almost six seconds off the day's best from Nico Rosberg in his 2011 Mercedes.

He did suffer one excursion off the track in the relatively cold conditions during the afternoon, but he was soon back out.

'I'm happy because I put in a lot of time in the car and that was the first time I've been on track since Monza last year, so I had to spend a bit of time this morning getting back into the groove, but that came pretty quickly,' said Van der Garde.

'There's a lot to learn but I know what I need to focus on so next time I'm in the car I'll definitely be able to get on the pace more quickly.

'We used both DRS and Kers today and I felt pretty comfortable with both. Basically I enjoyed myself today. The team has been great with me, so thanks to them and now I'm looking forward to my next run.'

Bruno Senna commenced his Williams career with the day's top lap tally – a huge 125 – but only topped Van der Garde in terms of time, while rather surprisingly it was Felipe Massa's Ferrari that could only muster eighth.

Grosjean completes the Jerez test for Lotus on Friday, when Jarno Trulli will get his first taste of the new Caterham.