Sauber prepares for Spanish GP

Diniz worked on the race set up of the car and, before stopping with engine failure, completed 83 laps, more than the equivalent of a race distance.

"I had two very good long runs today," said Diniz. "And I was able to get through a lot of important work for the Spanish Grand Prix next week. I'm sorry about the engine problem, as my aim had been to do 100 laps.

"But the car felt really good here and was very competitive in race trim, so I'm optimistic."

Jacky Eeckelaert, the head of Sauber's test team reiterated the necessity of such extensive testing, and shared Diniz's optimism for what had been achieved.

"Four days seems like a long time to prepare for a Grand Prix," said Eeckelaert, "but we have a complete programme to work through between Pedro and Mika Salo.

"We worked all day on race strategy and different mechanical set ups with the Red Bull Sauber Petronas C19 in race configuration.

"In particular we achieved a very good back to back with Bridgestone's hard and soft compound tyres. It was unfortunate that we had the engine problem, but in any case, the unit was close to its allotted mileage."

Mika Salo will take over on Thursday.