The 34-year old Karthikeyan covered 80 laps (320.4 km) and expressed satisfaction on the progress being made at the Ricardo Tomo circuit.
"We have been working through the programme. We did 80 laps, which is good. Obviously the times are not so important. We were not going for times today, just building up to it nicely.
"Besides, I have tried several Pirelli compounds, and therefore I feel really satisfied. Hopefully, we will do some more work tomorrow (Thursday) in the same direction," said Karthikeyan.
Karthikeyan's time on the second day, that was sixth quickest among the 15 ran timed laps, was a definite improvement as compared to his best of 1:18.0029 (45 laps) that he did Tuesday.
Karthikeyan looked to be in an excellent mental and physical shape, as he went through the familiarising process with his new team. "Narain has done once again a very good job in this second day of testing. Times are not now important as we pay attention to the data we are collecting," said team principal Colin Kolles.
"He has completed 80 laps, which is almost the double of what he did yesterday. I am very happy with his progress and I am sure he will keep on improving."
Force India's Paul di Resta continued the team's winter testing programme, completing more than 111 laps and clocking a best of 1:13.844 that was the third fastest, behind double World champion Fernando Alonso of Ferrari (1:13.307) and the 2010 winner Sebastian Vettel of Red Bull-Renault (1:13.614).
"Another good day of testing for the team, gathering lots of information for the guys to work on as we prepare for the debut of the VJM04 next week," said di Resta.
"At this stage, we are not going for times, just trying to get representative data to work on. I am feeling good and well integrated into the team and my new role."