The 2009 Honda Civic Si uses a six-speed manual transmission. There was no automatic option for the Si in that year, and the gearbox is paired with a helical-type limited-slip differential to aid traction.
Overview of the Civic Si drivetrain in 2009
Transmission specifics
Six-speed manual (6MT)
The core transmission is a six-speed manual gearbox. It features a close-ratio design intended to keep the engine within its optimal power band during spirited shifts, which is a hallmark of the Civic Si’s performance orientation.
Limited-slip differential
The 2009 Civic Si employs a helical-type limited-slip differential as part of the drivetrain, helping to manage power delivery to the front wheels under cornering and acceleration. This feature enhances traction and stability compared with a purely open differential regime.