Lucas di Grassi believes Virgin now has a good baseline to work from after finally completing some worthwhile testing mileage at Jerez today - but he warned that the team still has a long way to go.

Niggling problems, the late arrival of parts, a front wing breakage and the changeable weather meant Virgin managed few laps during the first three of the four test days. However today di Grassi had a trouble-free run, achieving 63 laps, with a best time of 1m22.912s, 3.3s off the pacesetting Lewis Hamilton's McLaren.

"It was very important for us to have a baseline to start working on the car," di Grassi told AUTOSPORT. "Today finally with the weather and with everything in place, we were able to do some running and have a baseline to start work for the next test."

He said he was carrying a representative fuel load when he set his best time, but that the team's embryonic status and his own rustiness meant it was not a true measure of what the car could do.

"I don't think we are the lightest car on the sheet and we are not the heaviest," said di Grassi.

"The last two years I've driven an F1 car for two and a half days, so I need to improve my driving, get more used to this new car - it has different feedback to what I was used to - and the same for the car, there's a lot of room for improvement in every aspect of the car. But as a baseline now we can start working on each of these aspects."

The Brazilian is confident that the VR-01 has fundamentally good potential once the team is up to speed.

"I think the most important thing with the car is that there is no chronic problem," di Grassi said. "There is no project mistake or anything. The car is doing well. It's behaving as a Formula 1 car, and now we just need to improve its performance and reliability."