Valtteri Bottas was fastest for Williams in mixed conditions on the final morning of the Silverstone young driver test, posting a 49.241sec lap on the International circuit.
Rio Haryanto, meanwhile, completed 79 laps in the Marussia with a best time of 50.405sec. Max Chilton took over for 22 laps in the morning, posting a 51.229sec lap.
The circuit dried out through the session but was damp enough initially for Haryanto to go out on intermediate tires before switching to slicks after an hour. The Marussia team coated the car in fluorescent aerodynamic paint in order to gather some data from the test.
Haryanto had been aiming to complete 300km over the two day test in order to get his Formula 1 superlicense and the team confirmed that he had achieved the required number of laps.
Bottas spent the first hour of the test completing engine temperature testing before heading out for an extended run totalling 62 laps. The Williams team fitted external measuring equipment to the rear diffuser for the later run.
Pos Driver Team Time
1. Valtteri Bottas Williams-Renault 49.241s
2. Rio Haryanto Marussia-Cosworth 50.405s + 1.164s
3. Max Chilton Marussia-Cosworth 51.229s + 1.988s
All Timing Unofficial