Lotus reserve driver Jerome D'Ambrosio says an extremely limited day of running was still enough to convince him of the car's potential.
The 26-year-old Belgian took control on the first day of Mugello, but managed just 10 dry laps as torrential rain led to an afternoon washout.
D'Ambrosio conceded conditions had been disappointing, but said he was still happy to have time in a car he labelled 'incredible'.
"Obviously with the conditions we were very limited in what we could do," he said, "but I could still get a bit out of the day and it is always good to get confident with the car.
"And then I had the feel of the car, which I think is fantastic. I was really limited, but even with 20 laps you know it - we have an incredible car. In terms of stability, how predictable it is, it is very nice to drive."
Asked how the Lotus related to the Virgin he drove in 2010, D'Ambrosio added: "You can't really compare - it's in another world. There is a big difference - a very big difference."
The Lotus reserve driver added that the rain had proved unwelcome both for him and for Lotus, disrupting the planned programme before Romain Grosjean takes over for the final two days.
"Supposing it was going to be dry - and we didn't get anywhere near that - there are things we wanted to try, thing you just don't have time to try on a race weekend. We wanted - we couldn't do it.
"The problem was in the afternoon there would have been value in going back out on inters and comparing to the morning, but in the end the condition was just too much rain.
"Of course as a driver you always want to go out, but you're also a professional and if the team doesn't want to go out you don't. The benefits are very limited: if the race was like this it would be stopped straight away. You don't go through these conditions, so there was just no point.
"It was definitely [disappointing]. We knew it, and in the end you can't do much about it, but it's disappointing because I should have done about 100 laps in the dry, and I did 20. Not just for me though, there were a few test items we wanted to try."