Kimi Raikkonen was pleased with his performance during his second day at the wheel of the E21, setting the fastest time to conclude an encouraging week for Lotus.
Though proceedings were interrupted by red flag periods including a lengthy pause for track run-off repairs, the Finn ran through a continued programme of aerodynamic assessments and was able to get the set-up of the new car more to his liking.
"We continued our work from yesterday and made some good progress," said Raikkonen.
"We're at the top of the timing monitors, but that means nothing in testing. Our focus has been testing parts on the car, but I've been able to get the set-up more to my liking. For sure there's more work to be done in this area, but that's what we're here for.
"The car feels strong and we seem to have a good idea of where we're going with improvements. Let's see what happens in Barcelona."
Lotus technical director James Allison added: "After the orgy of work at the factory to prepare the car over the winter months it is always a welcome relief once the testing campaign finally kicks off; not because the pressure backs off, but because we get a chance - finally - to see what we have been working on.
"It is tremendously exciting for the whole team, but very nerve wracking as well. We desperately want the performance to be good, but we are all aware of the thousands of potential traps in bringing a complex car to the track for the first time.
"We have had a good first test. The car seems competitive, and while there is always a background hubbub of problems to be solved, we are delighted with the basic reliability of the E21.
"With Jerez now behind us, our thoughts have already turned to Barcelona in ten days' time. There is a mountain of work ahead, but we are looking forward to our next opportunity to run the car."