Perez took his Mercedes-powered VJM07 around the Sakhir circuit in 1m 35.290s in the morning session, and with many teams opting to concentrate on long runs, the Mexican's time was not bettered in the afternoon.
"We really needed a good day to start this week and today we had it,” said a delighted Perez, who completed 105 laps in total.
“We managed to do a lot of laps, try several different (tyre) compounds and mappings, and it's been a fantastic day in terms of learning about the car. Tomorrow is my last day in the car before the season starts so hopefully we can have another solid day to be in good shape for Melbourne.”
Second on the timesheet was Valtteri Bottas in the Williams, who used a short run in the afternoon to vault up the standings. Prior to that, the Finn had concentrated on longer race simulation runs, racking up a day-high 128 laps in the process.
"It was nice to get the whole run plan done," said Bottas. "We didn't have any issues all day so well done to all the team for getting the car running so well. We have a lot of data to analyse tonight after doing some aero work this morning and a race distance and set-up work this afternoon. We did some very interesting tests and there are still plenty of things to improve so we'll keep pushing."
Behind Bottas was countryman Kimi Raikkonen. Technical issues restricted the Ferrari driver to just 12 laps in the morning, but the F14 T featured heavily in the afternoon’s running, completing a series of set-up tests over short runs before stopping again just before the chequered flag.
Last week’s overall pacesetter Nico Rosberg set the fourth quickest time of the day in Mercedes’ F1 W05 and was another to work on longer runs and set-up before a technical gremlin brought his programme to a slightly premature end.
“That was not a fantastic day for us,” Rosberg explained. “We tried some new parts on the car and you find out a lot through doing that. But unfortunately we did not only discover good things today.
“I managed to do a couple of good laps before lunch but in the afternoon we had a few small problems which ended my running a bit earlier than planned. This shows that we are pushing everything to the limit and we still have a massive challenge in front of us during the last three days of testing.
“We need to maximise our time here to be prepared for Melbourne. But after a difficult day overall we are on the right path.”
Adrian Sutil was the second fastest of the two non-Mercedes-powered runners in the top six, finishing with the fifth best time for Sauber, but he wasn’t entirely happy with his progress.
“We did a lot of mileage today,” he said. “However, we have to work on our performance. We still had a few issues. Nevertheless, we were able to do qualifying runs and almost a complete race simulation.”
In sixth place was rookie Kevin Magnussen who had another productive day at the wheel of McLaren’s MP4-29. The Dane completed a number of short set-up runs in the morning and a full race distance in the afternoon as he continued preparations for his Grand Prix debut in Australia.
Daniel Ricciardo gave world champions Red Bull some hope in the morning session when he took the so-far problematic RB10 around 32 times for P5. However, the overheating issues that have plagued the Milton Keynes-based team throughout pre-season returned in the afternoon and the Australian was only able to add another seven laps to his morning tally. Despite this, Ricciardo was upbeat about the progress the team have made.
“Behind the wheel, that’s the best I’ve felt so far,” he explained.
“The package seems to be coming together better. We still had a few issues today, but at least when the car was on track it was much more useful running and we made progress in the morning. It’s getting there.”
Another team looking to bounce back from a poor test last week were Marussia. Max Chilton showed the squad had put their IT problems firmly behind them by recording 44 laps and the eighth fastest time.
“We are all very pleased that we have made such good progress today and achieved our target of being able to run the MR03 in high and low fuel specification,” said Marussia team principal John Booth.
“We are reasonably happy with the performance of the car and the reliability is also starting to come, although these are complicated cars and we are treading carefully. There is only a short space of time now until Melbourne, so the work we will do over the next three days will be crucial.
“We have helped that process significantly by putting in place some firm building blocks for the rest of the week. We have had a challenging time in pre-season testing so far, but it looks like we are starting to turn the corner and motivation within the team is high.”
The other rookie on track on Thursday - Daniil Kvyat - had a mixed day for Toro Rosso. The Russian, who has struggled for mileage in pre-season, completed 43 laps in the morning, but a technical failure with the Renault-powered STR9 shortly after lunch confined him to the garage for the rest of the afternoon.
Rounding out the times were two other Renault-powered runners - Lotus’s Pastor Maldonado and Caterham’s Kamui Kobayashi. Both drivers suffered issues, Maldonado’s being an exhaust problem which sidelined him whilst he was evaluating new components.
“Today started well and we evaluated new aero parts in the morning,” said Lotus’s trackside operations director Alan Permane.
“Unfortunately, our new specification exhaust system failed, causing a small amount of damage to the surrounding area of the car. This stopped us running early due to the rectification work required.
“For tomorrow, we will run with our previous specification of exhaust and we do not expect to see any similar problems to those we saw today.”
The final test continues in Bahrain on Friday.
Unofficial Thursday test times from Bahrain
1. Sergio Perez, Force India, 1m 35.290s, 105 laps
2. Valtteri Bottas, Williams, 1m 36.184s, 128 laps
3. Kimi Raikkonen, Ferrari, 1m 36.432s, 54 laps
4. Nico Rosberg, Mercedes, 1m 36.624s, 89 laps
5. Adrian Sutil, Sauber, 1m 37.700s, 89 laps
6. Kevin Magnussen, McLaren, 1m 37.825s, 109 laps
7. Daniel Ricciardo, Red Bull, 1m 37.908s, 39 laps
8. Max Chilton, Marussia, 1m 38.610s, 44 laps
9. Daniil Kvyat, Toro Rosso, 1m 39.242s, 56 laps
10. Pastor Maldonado, Lotus, 1m 40.599s, 31 laps
11. Kamui Kobayashi, Caterham, 1m 42.285s, 19 laps