Fixing technical problems is taking mechanics up to four times longer than usual in F1's new turbo V6 era.
Writing in the Spanish sports daily Marca, Marco Canseco said the issue is so significant that a breakdown on the Saturday morning of a race weekend could mean the car is still not repaired by the time of the qualifying hour.
"Repair processes have at times been multiplied by four," said Canseco, referring to the multitude of breakdowns seen so far at the Jerez and Bahrain tests.
"If replacing a gearbox used to take an hour, we can now be talking about four. In the case of an engine, we can be talking about seven hours," he added.
Ferrari's Pat Fry is quoted as saying: "The cars are very complicated and it can take a while to just get in there and find the problem."
And a Toro Rosso mechanic told Marca: "The problem is that with the new power units, everything is packaged within millimetres.
"To find a faulty sensor that meant you stopped the car as a precaution can mean dismantling half the engine. Access is really complicated," he added.