BMW Sauber duo Nick Heidfeld and Robert Kubica have both questioned their team's plans to run third driver Sebastian Vettel on the Fridays of Grands Prix.
Vettel will be one of the few non-race drivers to get some serious running during the Friday free-testing sessions this year, with his team determined to give him as much experience as possible.
However, those plans have not gone down well with Heidfeld and Kubica, who both feel that their weekends may be compromised by the loss of track time.
With teams limited to two cars on track at the same time, any running that Vettel does on Fridays mean that one of the race drivers will have to sit out the session.
Speaking about those plans at the launch of the new F1.07, Heidfeld said: "Luckily we will not lose all of the Friday session, only half, but if you ask me that is already enough.
"If it was my decision I would drive all Fridays, Robert as well, I don't like it. But for me, that is enough."
Kubica added: "It depends what other drivers are doing. If the other top teams are using regular drivers then we should use regular drivers, but that is how it is. We will have to live with it."
BMW motorsport director Mario Theissen still believes he is doing the right thing in using Vettel because he believes it will benefit the whole team - rather than just individual drivers.
"I think it is important to have the drivers acting as one team, to have the transfer from a test to a race weekend situation and to develop the drivers and put them in a situation and make them acquainted with what they expect from a race weekend," he said.
"It is part of the team building process to have at least one of the test drivers driving on a Friday as well. It may not be all sessions, but we will always have a test driver there and always have him in a car."