Spanish GP: lack of DRS signal stymied Paul di Resta and Force India

The team had to instruct di Resta when he could use DRS via the radio as he was not getting the automatic signals into his car.

Deputy team chief Bob Fernley said it had been a complicated procedure.

"The signalling system at FOM level failed and we were manually trying to tell him where to use it," he told AUTOSPORT.

"It was not easy as we had to be sure that we were in the right [DRS] zone and it took a long time to find it on the various pages you need to go through to find out where that is.

"It happened quite early in the race - after he [initially] passed Rosberg, I think.

"We had a period of time when we had a bit of clear air so we didn't have to worry about it, but in the last bit we had to do it all manually."

Di Resta, who finished just 0.9 seconds behind Rosberg, added: "It was a very busy race in the cockpit."

Force India's other driver Adrian Sutil had also been a points contender until losing nearly a minute in a disastrous first pitstop.

"It was a crossed wheelnut," Fernley explained.

"Very frustrating as he made a wonderful start.

"I feel sorry for him because I think he could have had a very good result."

Sutil finished 13th, having run eighth in the first stint.