Romain Grosjean emerged at the top of the timesheets on day two of the opening F1 group test at Jerez, lowering the benchmark set by Jenson Button on Tuesday.

The Frenchman spent most of the day in P1, moving to the head of the pack before the mid-point of the day and then trimming six-tenths off that mark before the majority of the runners switched to focus on long run evaluations during the afternoon. Grosjean, who hands over the reins of the lone E21 to Kimi Raikkonen tomorrow (Thursday), ended the day with a best time of 1min 18.218secs, having completed 95 laps of the Jerez circuit.

"It was good today, as the programme went to plan and we showed we have good reliability," the Frenchman insisted, "For me, the whole test has gone well which bodes well for the year ahead. My feeling in the car is good and it was great to be at the top of the times. Even if it doesn't mean anything during testing, it's still good to be at the front."

Under blue skies, Grosjean worked through a programme of systems checks, temperature monitoring, data correlation, aero evaluation and tyre performance assessment., but ended his day stranded out on track after running dry.

We used the soft, medium and hard compounds and, whilst we're not 100 per cent yet on the differences between each, we have a good idea. Kimi [Raikkonen] will be working on this area for the next two days, so we'll have a better understanding when we head to Barcelona."

Second spot went to Paul di Resta, who appeared on course to rack up the day's highest lap total before having to hand his Force India car over to fellow Briton James Rossiter in the final hour. The Scot eventually matched Grosjean's 95-lap tally, and was only a couple of tenths shy of the Frenchman's target time by the time his day ended.

"We got through the programme without any issues," di Resta acknowledged, "We did some more good aero work this morning and then tried some set-up changes on the car. The handling of the car so far is good and I'm feeling comfortable after two days in the car. Testing is a good chance to make bigger changes than you would make during a race weekend and that's allowed us to really see how they affect the car and has given us valuable data on tyre performance."

Daniel Ricciardo led the way early on, pushing his Toro Rosso to a lap of 1min 19.487secs in the opening flurry of laps, but, despite being pushed back by both Grosjean and di Resta, managed to keep himself in the top three, eventually lowering his personal best by three-tenths. The engineers were able to carry out their first scan of the car in terms of set-up, while the day's programme also included some long runs to have a first look at the car in race trim.

"A few more laps today and a bit of a clearer picture of what the STR8 is like," Ricciardo noted, "We completed our programme, with short runs in the morning and longer ones in the afternoon, and also tried the medium [compound] Pirelli, having only used the hard yesterday, so, at least for this circuit, we have established a good comparison of the two."

The Australian managed to keep fellow countryman Mark Webber at bay, despite the Red Bull Racing driver being just a couple of tenths adrift of his junior rival and completing a session-high 101 laps in the new RB9.

"I think, in terms of consistency, it's great," Webber said, "I'm very happy with the car and myself. I might have bombed a few laps here and there, but I've done 170 or more, which is a good total for the first two days with a new car.

"The car gives me the confidence to push pretty hard and that's always an indication that you have something you can build on. We've learned a lot more since yesterday and I'm sure that will continue tomorrow with Sebastian [Vettel]. I think we've put the car in a good position for him and hopefully he'll be able to push on from there."

Nico Hulkenberg rounded out the top five for Sauber, squeezing himself in ahead of Lewis Hamilton after the Briton ran into reliability problems before the first couple of hours had run their course. Sauber focused on aero tests during the colder opening period, before switching set-up to focus on running with heavier fuel loads for the remainder of the day. Having run soundly throughout, however, Hulkenberg ran dry at the end of the session while the team conducted a fuel system check.

"It was a very good day, with Nico achieving all our goals," head of track engineering Tom McCullough confirmed, "We continued our work on understanding the Pirelli tyres and while, without doubt, the temperatures will be different once we go racing, we still got to understand them well. The car was, again, very reliable, which gives us a solid basis."

The same could not be said elsewhere in pit-lane, as Hamilton's problems compounded those already endured by Mercedes on day one, when Nico Rosberg suffered an electrical problem that took the rest of the allotted running time to rectify. The Briton had completed just a handful of lap more than his team-mate when he suffered a loss of rear brake pressure heading into the Dry Sack hairpin. Unable to sufficiently slow the W04 - locked fronts confirming his efforts to overcome the problem at the rear - Hamilton found himself bouncing across the gravel trap before coming to rest against that tyre barrier.

Although the driver was unharmed, the same could not be said for his car, which added suspension and bodywork damage to a work list that already included investigating the braking issue. As with Rosberg, Mercedes had to admit defeat well before the final chequered flag was waved, and will look for better fortune when the German returns to the cockpit on Thursday.

"We had a good start but then, unfortunately, we had a failure which brought our day to an early end," Hamilton sighed, "These things happen and it's all part of testing - and, of course, it's better that we get these small issues out of the way sooner rather than later. The guys are working really hard to overcome them.

"From the few short laps that I completed this morning, my general feeling was very positive. I got a good understanding of where the base of the car is and, whilst we need to do work in certain areas, it was good to have some laps to get a feel for what those areas are. I've told the guys that we just need to keep pushing and I know that we all will be doing that."

Ironically, Hamilton's best lap, which saw him sitting second overall at the time of his off, kept him ahead of the man who filled his shoes at McLaren, with Sergio Perez narrowly unable to better the Briton's 1min 19.502secs best as he made his first appearance with the Woking team.

Taking over from day one pacesetter Button, the morning kicked off with a continuation of yesterday's aero calibration work, carried out across a number of shorter runs. Attention then turned towards acclimatising Perez to the car, running through a prescribed programme of mechanical and aerodynamic adjustments with MP4-28 to give him a greater understanding of the inherent feel of the car and the way it reacts to set-up changes.

Felipe Massa was next up, his positive comments about the new Ferrari F138 notwithstanding. The Brazilian was the final driver to duck under 1min 20secs for the day, but remained 1.7secs off Grosjean's benchmark as the Scuderia preferred to concentrate on the items on its job sheet. While the afternoon was given over to aerodynamic testing and long runs, with Massa completing a total of 78 laps, he also accumulated a large amount of data relating to various exhaust configurations tried during the morning, which will now be analysed by the engineers.

"Today, we concentrated 100 per cent on the aerodynamic side and on the exhausts - in the morning, I didn't even do a flying lap because we used the time available to do constant speed runs and analyse various aerodynamic solutions," Massa revealed, "All the changes to the car took longer than planned but, in the afternoon, I managed to do three long runs which were very important in order to understand which direction we need to follow in the coming days."

The lone 2012-spec car in the field seemed destined to spend most of the day at the foot of the times, until Williams and Pastor Maldonado took to the track in earnest. The Venezuelan had just seven laps under his belt as the mid-point approached, but ended the day with ten times that number as he continued to evaluate parts that will appear on the team's new FW35 when it is launched in Barcelona.

"We had a clutch installation problem this morning, which was a bit disappointing considering it was the same as we had been running last season," technical director Mike Coughlan admitted, "We quickly remedied, this but it lost us time during our aero evaluations this morning, and we will look to recover this time over the next two days.

"This afternoon, the focus was back on tyre work and we also made some subtle set-up changes which has given us a good direction for the new car."

Maldonado ended the day half a second clear of Rossiter, who completed 19 laps after taking over from di Resta and managed a best lap of 1min 21.273secs on his first F1 appearance since running with Honda back in 2008.

"It felt great to be back in an F1 car and I was impressed with the performance straight away," Rossiter confirmed, "It's only the second day of running, yet the car already feels quite nicely balanced with a lot of potential. Having already done work on the team's simulator, it's good to get a feel for the real car and get acclimatised today so that I can really make the most of my running tomorrow morning."

The final two spots in the order were filled by GP2 graduates Giedo van der Garde and Luiz Razia, the latter getting his first run-out just and hour or so after being confirmed as Max Chilton's team-mate at Marussia. The Briton had been expected behind the wheel, but the Banbury-based team took the opportunity to get its latest recruit behind the wheel. The early part of the morning was given over to acclimatisation, but it wasn't long before Razia was making good progress and the team were able to start pushing through the list of test items. It was ironic, therefore, that Razia's day was cut short when the MR02 ground to a halt opposite the pits, and was denied a return to the circuit when the red flags reappeared in the closing stages.

"It is not the first time I have worked with the team, of course, but there has been a lot to take in and I need to get up to speed very quickly," the Brazilian pointed out, "I'm quite pleased with the way things have gone for me, so it is a shame that we were unable to run this afternoon. We had an engine problem, but took that opportunity to do our KERS checks and, overall, I think we have good reason to be positive as the guys are obviously pushing extremely hard."

van der Garde had trailed his former GP2 team-mate early on, but vaulted ahead once the Brazilian hit trouble and ended the day with a best effort of 1min 21.311secs, which put him two seconds clear of twelfth spot. The day consisted of aero and tyre evaluations as the Dutchman built on the experience he accumulated as reserve in 2012.

"Another solid day on track and, with 88 laps completed, we can be pleased with what we've achieved today," van der Garde reported, "For the second day running, we didn't have any real issues and we're working through the programme so the team on track and back in Leafield have a lot of data to work on.

Testing continues into a third day tomorrow (Thursday), with wholesale talent changes behind the wheel. Esteban Gutierrez and Valtteri Bottas are due to make their first appearances for Sauber and Williams respectively, while Pic takes over from van der Garde to make his debut with Caterham. At the other end of the field, Sebastian Vettel and Kimi Raikkonen are expected to take up the reins at Red Bull and Lotus, while Jean-Eric Vergne gets his turn in the cockpit of the new Toro Rosso.