Kamui Kobayashi: "After a couple of weeks to recharge we're back to work in Barcelona at a track everyone knows extremely well, but, unusually for us in the recent F1 era, this will be our first visit there this year as we didn't test there in pre-season. It's a track I've always gone pretty well at, especially in 2012 when I finished fifth after really good fights with Button and Rosberg in the race - while I'd like to be racing both of them again this year we're realistic enough to know that's very unlikely, but we are still aiming to be able to fight at least two of the teams ahead, and new parts should help that.

"We're bringing updates to the front and rear wings and the floor and the key to optimising the performance gains from them is obviously maximum time on track, so strong reliability will again be crucial. It was good to see how much progress we and Renault made on that over the first four races and we'll obviously aim to carry that over to Barcelona and throughout the season as it is especially important in helping perfect setups over the weekend."

Marcus Ericsson: "I've had a very good two week break back at home in Sweden but now I want to get back on track and Spain's the perfect place to do so! This will be the first race of the year at a track I know well and, while it's only a small advantage, it's obviously good to have that knowledge as it makes the initial runs on Friday more useful, and it means I can attack a lap more efficiently right from the start of FP1.

"That's important at any race, but especially this weekend as we have some new parts coming and it will be critical to complete the runplans we have for those on Friday so we can really see where we can find maximum laptime. As we have had at all the races this year, in addition to the work on track we'll also have the simulator operational back at Leafield, and all the simulation software we have at our disposal to help generate even more data, so while the focus will be on Spain there will also be a lot of work going on back at the factory to help us even more. Obviously that's a big step up in terms of support from the last time I raced GP2 in Barcelona, but for me it's all part of my progression and I can't wait to start work again!"

Spanish Grand Prix lowdown with Renault Sport F1 track support leader, Cedrik Staudohar

Main challenges of Spain for the Power Units: "We know Barcelona very well so we go to the race well prepared. The key points to look out for are the 1km pit straight: this will see the ICE flat out for around 10secs so making sure the MGU-H is efficient will help keep the battery reserve topped up. In the quick, flowing corners we'll need effective PU response while the slower corners demand good traction and stability under braking. Hopefully our new upgrades will deliver in both these areas."

Main energy recovery points: "Barcelona is very mid-table. The slow corners such as T10 and the chicane allow us to recharge the battery via the MGU-K. Fuel consumption is not a major concern here."

Difficulty rating: "Medium. We have so much information on Barcelona from previous tests that there won't be too many surprises. The majority of the workload will come from evaluating the new upgrades on the Power Unit software and chassis side."

What to watch out for: "We will have the next phase of the software upgrades in Spain so we expect improvements in both driveability and energy management. The improved response will be important in the low to mid speed corners and coming onto the straight."