Click the cost and confirm researching.If you have enough Combat XP, the research cost is displayed on a green background. The amount of Combat XP required to research modules is displayed on the unresearched modules. Click Research in the upper-right corner of the Garage to access the current vehicle’s Tech Tree.
You will need credits and experience to research new modules: Combat Experience earned in an Elite vehicle can be either used to accelerate crew training, or converted to Free Experience.
Common Tests, Sandbox Tests, and Supertests: Your Definitive Guide.