Relatively unchanged, the 2009 Mercedes-Benz S-Class offers an impressive array of power trains, from the S550 RWD and S550 4MATIC that are equipped with a 5.5L 32-valve V8 engine putting out 382 hp and 391 lb-ft of torque, to the S600 RWD powered by a 5.5L 36-valve biturbo V12 engine producing 510 hp and 612 lb-ft of torque. The AMG-built engines include the S63 6.3L DOHC 32-valve V8 engine generating 518 hp and 465 lb-ft of torque, while the S65 has a 6.0L SOHC 36-valve biturbo V12 with 604 hp and 738 lb-ft of torque. Exhibiting exemplary performance, especially for a large luxury sedan, the S-Class handles 0-60 in the 4.2- to 5.4-second range. All S-Class trims are equipped with an automatic transmission, providing seven speeds except for the V12 trims, which have a five-speed transmission. Mercedes-Benz S-Class fuel economy estimates for the S63 AMG and S600 are 11 mpg city/17 mpg hwy, while the S65 AMG and S550 4MATIC get 14 mpg city/20 mpg hwy, and the S550 increases hwy to 21 mpg. Safety features are top-flight, as expected.