Norris acknowledged the improvements the team were able to make to the car over the course of the season but said there is definitely more room for improvement in how the car works under different conditions.
He also spoke about improving other aspects of the team, such as during pitstops and overall car reliability, which the team suffered from both throughout the season.
"Downforce, it's as simple as that," Norris said when asked what McLaren needs to improve on. "Downforce is always the biggest thing, and it's one of the biggest things that improved from last year.
"It's not just having more downforce, but efficiency, characteristics of the car, the car still needs to work in different conditions, different winds, different cornering types and speeds.
"There are still things from our stop like pit stops, driving, that we need to improve, and our efficiency on how we want to work as a team.
Norris also spoke of the importance of developing a car that can work throughout the whole season, saying that the team need to work on a car that can suit various circuits across the calendar in order to get the maximum from the overall package.
"But also with the car, the car is suited to some tracks and some tracks not at all. Trying to make the car suit both, but not so much one track but also be competitive at the tracks we suffered at a lot more.
"Characteristics of how the car works and so on is the biggest thing to improve."
Bahrain International Circuit - Winter testing