Romain Grosjean says he is still searching for the optimum balance despite finishing firmly inside the top 10 during second practice for the Austrian Grand Prix.
Grosjean was seventh quickest at the Red Bull Ring but his best time was three-tenths of a second slower than the one achieved by Lotus team-mate Pastor Maldonado, who ended running in fourth position.
"The car felt good, but we’ve still got some work to do ahead of the race and qualifying," said Grosjean.
"The balance wasn’t quite where I wanted for my fastest run on the super soft so we’ve got some progress to make for qualifying.
"Pastor went well in the same conditions, so we can see there’s pace to be found. For the race we’ve got to work on some of the set-up but there is good potential for the weekend ahead."
Maldonado was encouraged by a comparatively trouble-free day's worth of running in the E23 Hybrid.
"The day was pretty straight-forward actually," he said. "We had no dramas so we were able to work through our programme and make good progress.
"I think there is still some potential for more pace from the car and then we should go well tomorrow and in the race."