De la Rosa plays down tire performance reports
Although often impressive in the February tests, it was previously not thought the Ferrari-powered C29 would be good enough to trouble the top four teams this year.
But a Bridgestone official said earlier this week that the Sauber has proved better than all its rivals in terms of looking after its tires on long runs, which given the refueling ban could prove a significant strategic advantage.
Team boss and founder Peter Sauber said: "I've said it many times: interpreting the results of testing is like reading tea leaves. After all these years I have become quite cautious."
Speaking with reporters at the Sakhir circuit on Thursday, the team's Spanish driver de la Rosa agreed.
"I don't think that the tire information is that relevant because we come from winter testing where the track temperatures were very low and now we come to reality.
"The way the teams use the tires will change dramatically from how it was in Barcelona," the 39-year-old added.
More strident in Bahrain was Nico Rosberg, who is reported to have an even better grasp of Mercedes' new W01 than his seven time world champion teammate Michael Schumacher.
"I feel very, very comfortable in the car, very confident," the 24-year-old German said in a morning press briefing in the island Kingdom.