The young Briton was only able to set his personal best time in the last 40 minutes of his programme on Thursday amid an interrupted session.
But he remains confident that the team's 2013 design has addressed issue with last year's.
"Until the afternoon we didn't really know [if the car was a step forward] because we've either had an issue or a red flag," Chilton told AUTOSPORT.
"After doing some mileage we could actually see how the car was handling. I know it shows some potential and the team knew too, so when I came back [to the pits], we had smiles all around."
Chilton believes front-end grip is a particular improvement.
"I think as a team we struggled with the front end last year, and being in the debriefs last year with Timo [Glock] and Charles [Pic] last year I knew the limits and factors with it [the car]" he said.
"But when I pushed, I noticed in the long runs there was an improvement in that area, and that was definitely more positive."
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