Sergio Perez says he is "not very confident" with his MP4-28 as the "inconsistent" car played a role in his Friday incidents.
The Mexican driver crashed after the chequered flag had fallen after Friday's first session, going off into the gravel and hitting the barrier at the pit lane entry.
With the front of his car repaired, Perez was back in action for the afternoon's session only to tap the barriers again, this time at Turn 8 and with the rear of his McLaren.
"It was a very difficult day for myself with the crash in FP1 and the off in FP2," Perez told Autosport.
"We don't really understand what happened: I had a lot of wear, the front tyres were losing temperature and as soon as I hit the brakes I locked the tyres, [but I was] not pushing at that point.
"I'm not very confident with the car and that makes things difficult.
"We have so many question marks, we have to analyse everything that we have done because we don't know which direction we are going. The car is so inconsistent for us."
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