The standard transmission is a 6-speed manual with an optional 5-speed automatic. Base (Standard) and Limited models, originally sold beginning in the 2004 model year, are equipped with a Mercedes-Benz M112 3.2 L, 18-valve, SOHC V6 engine which produced and of torque. SRT-6 models were equipped with a supercharged version of the M112 engine built by Mercedes' performance branch, AMG. SRT-6 models came only with the 5-speed automatic transmission, consistent with AMG cars of the same era. The 6-speed transmission used by the Chrysler Crossfire is a variant of the Mercedes sourced NSG-370. The 5-speed automatic transmission in the Crossfire (known as 5G-Tronic) is also Mercedes sourced and a variant of the 722.6 family. The automatic achieves a better EPA fuel efficiency rating over the 6MT, mostly due to the difference in gear ratios.