The Briton tested the W10 on the second day of Bahrain testing, ending the day on top of the timesheets.
It offered a pleasant change for the 2018 Formula 2 champion, who has had to deal with a far from competitive Williams car, that is languishing at the back of the field.
Speaking about the test, Russell stated: “It was an incredible experience, an experience not many other drivers ever get to try,” he said.
“They are currently leading the world championship, you could argue the fastest car on the grid at the moment - so for us at the moment, in our current situation, it was a great opportunity to know what we should be aiming for.”
Although he is unable to share confidential information from the test, Russell believes that there is a lot that both he and Williams can learn from the outing.
"We did agree I can’t come back and share confidential bits, but I’m capable of coming back and saying their car is doing X in these corners and our car isn’t and this is what we need to be working towards,” he said.
“I think it was a very good test and obviously we all know they have developed more downforce than us – but there’s more to it than that.
“The differences are as expected. If you look at the timesheets and look where Williams are and where Mercedes, the differences are exactly as you would imagine.”
As Williams is set for another difficult weekend in China, Russell says that there is no easy answer to when the team will fix its problems and return to the midfield pack.
"Everyone is working as fast as they can to try and improve but in F1, everyone improves. So we have to not only improve but improve at double or triple the rate of everyone else, which in reality is extremely difficult.
“We have to stay positive but also be realistic. Realistically, we can’t be aiming for much more than we are achieving at the moment. Everyone is developing. We have to find some magic to try and overcome that.”