What is Two-step?
A two-stage rev limiter system. The first stage holds engine RPM at launch level; the second is the regular redline. Used for drag racing launches.
Two-step is a two-stage rev limiter system used in performance cars. The first stage (the launch limit) holds the engine RPM at a specified level (typically 4,000-5,500 RPM) when the launch button is engaged or when launch control is active. The second stage is the regular redline (typically 7,000-8,000 RPM). The driver can hold the engine at the launch RPM with the throttle floored, then release the brake to launch with the optimal RPM.
Two-step systems are common in drag racing applications and are increasingly available as factory features in modern performance cars. The Volkswagen GTI launch control, BMW M Driver Logic launch control, and various other production launch control systems include some form of two-step. Aftermarket installations through engine management can add two-step to cars without it.
The two-step provides launch consistency. Without it, launching requires precise foot coordination (holding the brake while modulating throttle to the optimal RPM). With two-step, the driver can simply hold the throttle pedal and brake fully, then release the brake when ready. The result is more consistent launches and lower variation between runs at the drag strip.
