Force India's B-spec 2015 F1 car delayed to British Grand Prix

A switch of windtunnels to Toyota's facility in Cologne and issues with suppliers meant the manufacturing of the 2015 chassis was delayed.

Initially, Force India hoped that the updated car would run in Monaco, but deputy team principal Bob Fernley told AUTOSPORT last month that it had been delayed until Austria.

Despite the team completing its windtunnel programme at the end of April, which was earlier than planned, to enable the manufacturing process to begin, the plan is for the car to make its race weekend debut at the British Grand Prix.

Perez said: "We are obviously pushing very hard back at the factory trying to bring the package together.

"We would love to have it for Barcelona but that didn't happen so I think Silverstone will be the first time we have a new package."

Despite suffering from a lack of pace relative to its rivals, Force India has limited the damage in the constructors' championship.

Having scored points three times, the team is just one point behind Lotus and Toro Rosso after four races, with Red Bull just 12 clear in fourth.

"We have been lacking a lot of pace so the effort in the first four races has been pretty special considering where the basic pace of the car is," said Perez.

"I think we have pretty much maximised the current car.

"This race [in Spain] will be particularly difficult, considering what this track is like regarding downforce as this is where we are lacking the most.

"We do not have any upgrades but some of the other teams are bringing upgrades.

"But we have done an amazing job to be just one point from Lotus and 12 points from Red Bull.

"It's a good effort from the team so when the upgrade comes, we should be in a strong position to fight back and challenge them."