British Grand Prix the key test for Force India F1 team's upsurge

Since updating the aerodynamics of the VJM09 for May's Spanish GP, Force India has been the fourth highest-scoring team in F1, and has finished on the podium twice in the last three races with Sergio Perez.

Szafnauer says Force India has been getting stronger as it better understands how to extract performance from the Barcelona update package, but reckons the high-speed challenge of Silverstone will be a better test of its aerodynamic prowess than F1's recent run of street-style circuits.

"The car is stronger since then [Barcelona], and the only little backward step we took was in Canada [where the drivers finished eighth and 10th] - we thought we'd be a little stronger there," Szafnauer told Autosport.

"I think that was a little bit to do with the temperature and how we treated the tyres, but we learned from that.

"We've got Austria and Silverstone coming up; Silverstone will be a big test for us.

"If we're strong at Silverstone, we'll be strong at all the tracks coming up."

Force India has closed to within 31 points of fellow Mercedes customer team Williams in the constructors' championship after finishing third and ninth in the recent European GP in Azerbaijan, but Szafnauer said the team is still wary of threats from behind.

"They [Williams] have got a decent lead on us, we'll just keep doing the best we can and see how it progresses," he added.

"We also have some great competitors behind us - Toro Rosso are strong, McLaren are always getting better, so we've got to watch our backs as well."