"We made a lot of improvements and we feel like there's more time in both myself and the car and so I think we feel good about where we stand both tomorrow and then on into Sunday," said Rahal, who was happy with his best time of 1:02.2924s (104.026mph).
Dixon improved his time in the afternoon to 1:02.3117s (103.993mph), better by almost seven tenths from the benchmark he had set as the fastest man in practice 1, but he was obviously nonetheless disappointed that so many other cars had caught up and passed him.
"We made a number of adjustments in the second session and I think we over-adjusted and got the car too loose," he mused afterwards. "Looking back now I think we should probably have been higher up on the scoring charts."
Inevitably, there were problems elsewhere in pit lane. New series star Rubens Barrichello suffered mechanical problems in the morning that ate into his track familiarisation time and left him languishing down the timesheets at the end of the day.
"With the problem we had this morning, it was pretty much a setback," admitted the former F1 driver, who is finding St Pete a very different sort of track from the Grand Prix circuits that he's used to. "I spent the afternoon session learning the track, while everyone else was now improving their cars. I was playing catch up big time that's for sure. Hopefully tomorrow I can improve a little more from today."
Simon Pagenaud's #77 Schmidt-Hamilton Motorsports car was also struggling, with the team's Honda engine becoming the first power-plant casualty of the weekend. As a result he'll take a ten-place grid penalty for an unauthorised engine change. No other engine or mechanical failures were reported on Friday.
"It's just a shame we can't run more this afternoon," said Pagenaud, finally running full-time in IndyCar this season after being the series "supersub" in 2011. "Something didn't feel right, and I shut it down to be on the safe side. It is what it is, and that's racing."
Up till then, he'd been very happy with the way the car was developing, and of course the street circuit was very much playing to the former sportscar star's strengths. "I love street circuits; they provide you so much adrenaline rush. I still think we'll be good tomorrow."
Charlie Kimball provided the only real accident of the opening day of the 2012 IndyCar when he went into the tyre wall at turn 10 nose-first near the end of the first session. There were two red flags in the afternoon, one for Pagenaud stalling at the entrance to pit land and a later one for Dale Coyne Racing's James Jakes spinning and stalling his #19, but neither were serious affairs and Jakes' optimism for a good showing over the weekend as a whole was undiminished.
"Overall it was a pretty good day for the #19 Boy Scouts of America car," he said. "There are a couple things we need to work out with the car, but I am very confident that we will have a good qualifying session on Saturday afternoon."