The Briton finished a comfortable 1.4 seconds clear of the field on the second day, although his best time of 1m 34.136s was set on a development tyre - Mercedes having agreed to dedicate the day exclusively to compound work for Pirelli.
Each of the 11 teams will do likewise over the eight days of in-season testing, with Caterham and Williams having joined Mercedes as Pirelli’s designated teams for the Bahrain test.
Hamilton was also the only driver to break into triple figures in the lap count, completing 120 in total. That was in stark contrast to Ferrari, whose attempts to improve their form suffered a setback when they were forced to abandon running as a “precautionary measure” when the chassis of Fernando Alonso’s F14 T was found to be damaged. The Spaniard managed just 12 laps.
Jean-Eric Vergne, taking over from team mate Daniil Kvyat at Toro Rosso, went second fastest after focusing on aero work and data acquisition.
“It was not a completely trouble free day, but that’s what testing is about,” the Frenchman said. “We got some serious work done today that can inform us on the way to move forward for the next part of the season. From that point of view, today was very productive and important.”
McLaren opted to stick with Kevin Magnussen on day two, but he also suffered problems as a mechanical issue sent him into the gravel just before midday.
Fresh from his podium on Sunday, Force India’s Sergio Perez clocked the fourth fastest time, just ahead of Red Bull’s Daniel Ricciardo and Marussia’s Jules Bianchi. The Australian was delayed by an electrical problem in the morning, but was able to undertake aerodynamic work in the afternoon. The Frenchman, meanwhile, spent the morning exploring various set-up options on Pirelli’s medium compound, before moving onto analysing brake developments in the afternoon.
Sauber reserve driver Giedo van der Garde took over from Russian rookie Sergey Sirotkin for the second day, but had to contend with power unit gremlins in the morning. He eventually managed 77 laps en route to finish seventh fastest – more than three seconds down on Hamilton, but still ahead of Alonso.
"We found something interesting during the long runs in the end," said Van der Garde. "Besides that, I think the performance run was also quite good as it was during the hottest part of the day, so the time was pretty good.
"All in all, I am happy that I got the chance to drive the C33 again and I am looking forward to being back behind the wheel for FP1 in China.”
Caterham were also waylaid by early technical problems on what was a very hot day, with temperatures in excess of 30 degrees Celsius. The team managed to fix its ERS complaints however, and Marcus Ericsson completed 66 laps by the close of play.
That was two more laps than Williams’ reserve driver Felipe Nasr managed. The Brazilian, like Hamilton, spent the day doing development work for Pirelli.
Lotus rounded out the timesheets, with Romain Grosjean suffering power unit issues as he completed just 16 laps in total, the fastest of which was over nine seconds off Hamilton’s best in the F1 W05.
Unofficial Wednesday times from Bahrain:
1. Lewis Hamilton, Mercedes, 1m 34.136s, 120 laps
2. Jean-Eric Vergne, Toro Rosso, 1m 35.557s, 64 laps
3. Kevin Magnussen, McLaren, 1m 36.203s, 26 laps
4. Sergio Perez, Force India, 1m 36.586s, 63 laps
5. Daniel Ricciardo, Red Bull, 1m 37.310s, 67 laps
6. Jules Bianchi, Marussia, 1m 37.316s, 93 laps
7. Giedo van der Garde, Sauber, 1m 37.623s, 77 laps
8. Fernando Alonso, Ferrari, 1m 37.912s, 12 laps
9. Marcus Ericsson, Caterham, 1m 39.263s, 66 laps
10. Felipe Nasr, Williams, 1m 39.879s, 64 laps
11. Romain Grosjean, Lotus, 1m 43.732s, 16 laps