The Brazilian has been testing the F138 at Barcelona today as part of the second winter testing event.
The 31-year-old told Sky Sports News: "We didn't change anything really, no new pieces or anything, so the car is exactly the same as we finished Jerez. For sure we understood maybe the little details around the car that maybe we change again for here. It's like an evolution but not with new pieces or anything.
"The car is still 'green' so we need to make the car in a good shape for the first race. There is a lot to work on, there is a lot to do, and maybe it's a very important moment as well for people working on the aerodynamics, on the engine, on the chassis to put everything together in a good direction for the first race.
"I feel okay and I feel good in the car but I didn't drive for a long time in the car so it's important we use the next week very well."
Massa and teammate Fernando Alonso will get another chance to trial the car next week at the final testing session before the Australian Grand Prix.