Felipe Nasr says 2016 Sauber Formula 1 car better in all areas

The team ran last year's car at the first pre-season test after adjusting its plans due to a late change to the F1 calendar.

Nasr had a trouble-free day, covering 103 laps, and is hopeful Sauber now has a solid base to work from.

"To have clocked that amount of laps on the first day is quite impressive as you normally expect there to be more things that need to be fixed," he said.

"It was a smooth day overall and though there were some small issues, they was nothing major.

"The early impression was quite good. It felt like a step forward from last year in terms of the chassis, engine and gearbox.

"It felt like we had a step forward on everything."

Sauber struggled with rear instability last year while Nasr personally had problems with overheating the brakes.

The Brazilian says initial impressions suggest Sauber, which is running in Melbourne-spec, has made improvements in those areas.

"As a back-to-back on the car from last week, it felt like we had a more stable rear when looking at medium and high speed corners," he said.

"Last season, I had a lot of problems overheating the brakes.

"The package seems to be improved on cooling and it gives us margin to play with the brakes so we can push it further."

Nasr also gave the Ferrari power unit, which proved crucial in helping Sauber score points early on last season, a ringing endorsement.

"The engine has impressed me in terms of the drivability being better," he said.

"The whole response of the engine in all speed ranges was more progressive and more consistent as well.

"The feeling is a lot better and this has helped to calm down the rear of the car. There was a good job there."

Technical director Mark Smith said he did not think starting a week later than other teams would "hurt us too much".

Asked about his feelings on the impact on the team, Nasr said: "If I had the car one week earlier, it would have given more time to get other areas further developed.

"But it is what it is, we have to focus on what we have got now."