Jolyon Palmer says it has been a positive start to life with Lotus after spending time in the E23 at the Circuit de Barcelona.
The British newcomer, who signed as the team's test driver earlier in the year, had his first taste of the new E23 on Friday.
Covering 77 laps on the day, Palmer crossed the line with a best time of 1:26.280, which was 1.706s slower than the P1 time.
"It went well. We racked up a lot of laps and I got a good feel for the car," he explained.
"It was very slippery first thing with the cold track, it was certainly very difficult with the hard tyres combined with the low temperatures!
"Through the day there was a good mix of conditions and set-ups to work with. There was a lot to take on board with the different settings for the car and the different programmes we were running, so it’s been a pretty steep learning curve.
"It’s been a very positive start for me and I hope my work has benefited the team. I loved being in the car and I can’t wait to get back out on track!"
Trackside operations director Alan Permane was impressed with the new test driver and is confident Lotus are moving forward with the new car.
He said: "Today was about data accumulation and Jolyon did a great job in his first time in the car, especially with particularly cold conditions to start the session here this morning.
“We’ve completed a number of aero runs with a variety of different data collection tools on the car as well as conducted a number of different tyre assessments to build a picture of what to expect from Pirelli’s latest tyres working on the E23.
"The car has run well again and overall we’re making good progress this week."