Eric Boullier says Lotus are happy but not confident as the second of the pre-season tests draws to a close.
Lotus spent the last four days lapping the Circuit de Catalunya in Barcelona and although the team did not set the pace on any of the days, rivals have made note of the E21's pace.
"The Lotus has been very good," said Sauber's Nico Hulkenberg after Romain Grosjean's race simulation on Thursday.
"We didn't do the same programmes, and his fuel would have been down by then so you can't tell [fully], but that [wasn't] a bad effort. From how my own tyres felt, [Grosjean's stint] wasn't bad."
Lotus, though, are refusing to get carried away as Boullier concedes there is still some way to go before F1 heads to Australia.
"Confident, no, but happy, yes," the team boss told Autosport.
"I know that next test everyone is going to bring a Melbourne spec, so we will see next weekend how it is going.
"Then you can stop to draw some conclusions. But the race is in Melbourne."
The Frenchman revealed that Lotus will be updating the package ahead of next week's final test and hopes that when his rivals do the same, they won't suddenly find a massive advantage.
"After today, I hope nobody will find one-second of performance between now and then, it doesn't work like this."
He added: "It should be a reasonable upgrade."