Although happy with his RB9, Mark Webber admits Red Bull need to continuously develop the car or risk getting their "arse kick."
The Aussie was in action at the Circuit de Catalunya on Friday where the rain hampered Red Bull's programme.
Webber, who spent a large part of the day focusing on pit stops, completed 64 laps with a best time of 1:27.616, which was over four seconds off the pace.
"We know that if we keep this car for three months we are going to get are arse kicked; we need to keep developing the car," he told ESPN.
"Thankfully a lot of other teams talk about that but we like to do it on the track.
"We will try and do the same again this year and we have a target on our back. We enjoy our racing, we like the success and we'll try to keep it up."
The 36-year-old concedes part of the car's performance is based on how it handles the Pirelli tyres and says Red Bull will focus on this at next week's third and final test.
"Next week we will continue our ongoing investigation into the tyres, learning more about those.
"We also will be checking how they are going in different temperatures, day two was probably the best in terms of temperatures when the sun was out.
"That will be right on the top of our list and some more performance stuff that you have to keep putting on the car to stay towards the front."
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