The Venezuelan and new team-mate Valtteri Bottas are running last year's FW34 at this week's Jerez test, with the focus on understanding the 2013 Pirelli rubber.
But as well as the new tyres, the car also includes a number of 2013 development parts, most obviously the vanity panel fitted to shroud the step in the nose.
"We are confident with the new car," Maldonado told AUTOSPORT. "But we want to be even more confident.
"With the test we planned to do here, there is no better way to do it than with the other car because we have a lot of confidence in it, a lot of data to compare and we are going to be more clear [in understanding the tyres] with it.
"We are trying small parts in the car, different things and different settings to try and understand the components.
"It is very important to be here with the old car."
Maldonado, who claimed a shock victory in last year's Spanish Grand Prix, is certain that the new car will be an improvement on last year's machine.
The team believes that its 2012 car was good enough to finish fifth in the constructors' championship, three places higher than it ultimately did, and Maldonado expects even more from its successor.
"It's a step," said Maldonado. "We try to look at every single component, everything.
"But all the cars look very similar to last year because the rules are the same.
"It's a small improvement all round the car and we are quite confident that it will be very competitive this year, even better than the previous one."
Maldonado added that the team still has some way to go with understanding the tyres having run exclusively on the soft compound on Tuesday.
The team's Wednesday running has been limited because of a clutch problem that manifested itself during his first run.