Italian Giancarlo Fisichella boosted the morale of his Force India team on Friday by posting the fourth best time in testing at Barcelona's Circuit de Catalunya.
"I think we made a lot of progress," the 35-year-old Roman said in a team statement after completing 100 laps in the team's Ferrari-powered interim car without any major mechanical problems on a cold day at the Spanish track.
"I felt more comfortable in the car too -- we are definitely going in the right direction and the times were pretty good. I'm very happy as we are showing the potential we have now," added the former Renault driver.
Fisichella's best lap was 1:23.015, 0.8 seconds quicker than the team's fastest time in qualifying for last year's Spanish Grand Prix and Force India said the car had not been particularly light on fuel.
Force India's predecessors Spyker scored just one point last season.
With champions Ferrari absent, McLaren's Lewis Hamilton topped the timesheets in 1:22.263 according to unofficial timings.
McLaren, whose new MP4-23 car passed the mandatory FIA crash tests earlier in the week, said the Briton had focused mainly on tyre evaluation.
Renault's double world champion Fernando Alonso was second fastest, a day after the new R28 was launched officially in Paris. Poland's Robert Kubica was third for BMW Sauber.
"Today we put some new parts on the car which we had introduced in Valencia and we tried to evaluate them. Everything was positive and went according to plan but tomorrow is when we will start the real programme," said Alonso.
Williams halted their running on the first day of a test that continues through the weekend after a front wing mounting problem caused Japan's Kazuki Nakajima to crash into the barriers. A spokesman said they would be back on track on Saturday.
Honda, who launched their new car on Tuesday, again languished at the bottom of the timesheets, with Brazilian Rubens Barrichello doing 55 laps with a best time of 1:24.125 and Austrian test driver Alexander Wurz even slower in 1:26.975.
Red Bull kept the photographers busy with Australian Mark Webber driving their new RB4 car with a radically re-designed engine cover.