Paul di Resta believes a leaner, keener and happier Force India team are ready to make an impact in Formula One this season.

Di Resta enjoyed a solid two full days of testing in the VJM06 at the Circuito de Jerez, clocking up 181 laps, before a further half day yesterday following a morning run from James Rossiter.

For the Scot, the extended track time was simply an extension of the good vibe he has picked up on at the team's Silverstone factory this year.

"Their approach this year has changed," said Di Resta. "Something seems to have taken on another level in terms of the department, with how we are working and networking.

"It's difficult to put into words what it is. It's just everybody appears quite relaxed but equally keen and eager, and relatively quite content with the car we have developed.

"Given the reliability of the car over the past two days, that gives you a direction as to where it is.

"We're achieving a lot, putting in the miles, everybody is organised, the parts are arriving on time, we're pushing the departments to the extreme to make sure they come up with bigger and better things.

"So we're working away as a team. Everybody in the garage looks a bit leaner, the sun has been shining and it has been a good few days.

"Given where we finished last year, and with some of the results we had, we're certainly hoping to go up a stage.

"Whoever you are battling with, the aim for a team like us is always about getting the next constructor ahead of us."

Given the lack of a full-time team-mate this week, with Force India now the only one without a second driver, Di Resta has found himself leading the team.

It is almost certain a replacement for Nico Hulkenberg will be in place for the second test in Barcelona in a fortnight.

But Di Resta is enjoying the responsibility, adding: "It's not affecting me. I'm working away with the people I feel I have to."