Gundam Extreme Vs. Maxi Boost [Japan Arcade] - S Drive & F Drive Gameplay System
One of the new gameplay additions is the EX Overdrive, which appear to be tied to the EX Gauge and replaces the Assault and Blast Bursts altogether. This mechanic comes in two types; S-Drive and F-Drive, the former which upgrades firearms and the latter which improves melee attacks significantly. These can be activated once certain requirements are met. In addition, navigators can now be chosen in VS battles and will comment on your performance during battle. Lastly, many units will be receiving cost tweaks as well as new cost values of 1500 and 3500.
Info via gundam.wikia.com
F DRIVE (Red Color Ring when activated)
Increase close combat / melee performance
S DRIVE (Blue Color Ring when activated)
Increase long range / weapon firing performance.