Felipe Massa said that his first day of running with Williams was a 'special' experience.
Massa has switched to Williams after eight years with Ferrari and set the second fastest time, having completed 47 laps at Jerez.
"It was a very special day, the first day I drove with a different engine in Formula 1," he said after his first experience of the Williams FW36.
"We didn’t do as many laps as we expected to do. Unfortunately many times you have a little issue and it takes a lot of time to change. Others are struggling more than us but I’m happy with the day, I'm happy with the first feeling and the first impression with the team, driving the car, the engine, the car itself, the tyres, gearbox, everything."
"It was a good start. [Williams are] a professional team, a team that can do a very good job in Formula 1, not a team there to fight in the back but in the front, something that makes me even more happy."
Massa said that the cars felt different to drive, compared to last year's machines.
"It's a big change definitely, not just the engine but the rules. The car has a lot less downforce, The drive-ability is different, the engine is different, the torque is different, the torque map is different. You need to understand how to drive, sometimes you just go sideways and sometimes you do a short shift and you gain lap time. So the understanding is very important but I think it was a good feeling for the first time."
Massa also believes that a podium is possible if a driver can simply finish the first few races.
"For sure everybody has problems to solve, everybody has some little issues and we have [too]."
"It’s something we need to fix as quickly as possible. [The] first races will be very important to finish, if you finish the first races you have a chance to score good amount of points or even a podium. We need to look for long runs and reliability, to fix all the little issues that can make you stop the car in the race. Performance is always important but reliability is maybe a little more important."
Massa commented on the differences between the three engine suppliers, believing that it felt like there were three different categories.
"It's a big difference from car [to car]. Not the performance but Mercedes compared to Ferrari compared to Renault. It looks like three different categories. I'm not talking about performance, I just mean the noise. Everything is different. Its difficult to understand who has done the better job."