Initial Quality – In the J.D. Power and Associates 2008 Initial Quality Study, the Mercedes-Benz S-Class received an Overall Initial Quality Power Circle Rating of 4 out of 5.

Performance and Design – In the J.D. Power and Associates 2008 Automotive Performance, Execution and Layout Study (APEAL), the Mercedes-Benz S-Class was the highest ranking Large Premium Car, receiving an Overall Performance and Design Power Circle Rating of 5 out of 5.

Predicted Reliability – The current generation of the Mercedes-Benz S-Class was a new model for 2007 and is too new to have been included in the J.D. Power and Associates 2009 Vehicle Dependability Study (VDS), which measured dependability of 2006 model-year vehicles. However, based on the performance of previous S-Class models during the past five years in both our Initial Quality and Vehicle Dependability studies, the predicted reliability rating for the 2009 Mercedes-Benz S-Class is 3.5 out of 5 Power Circle Ratings.

Fuel Economy – The 2009 Mercedes-Benz S-Class is equipped with one of four engines, ranging from a 382-horsepower, 5.5-liter V-8 engine to a 604-horsepower, 6.0-liter twin-turbocharged V-8 engine, each requiring premium fuel. The most fuel-efficient S-Class is the S550 with rear-wheel drive, which is rated to achieve 14 mpg in the city and 22 mpg on the highway (the highway rating drops to 21 mpg for the all-wheel drive S550 4Matic). The least fuel-efficient S-Class is, well, the rest of the lineup. The S600 with the bi-turbo V-12 engine, the V-8-powered S63 AMG, and the bi-turbo S65 AMG are all rated to deliver 11 mpg in the city and 17 mpg on the highway.

Our review vehicle, an S550, averaged 16.6 mpg in mixed driving. Combined with the S550’s standard 23.8-gallon fuel tank, this actual fuel economy figure results in an approximate 395-mile range between fill-ups of premium unleaded.

Safety – Neither the National Highway and Traffic Safety Administration (NHTSA) nor the Insurance Institute for Highway Safety (IIHS) has performed crash-test procedures on the Mercedes-Benz S-Class.

Environment – According to the EPA, the 2009 Mercedes-Benz S-Class consumes between 20.1 and 26.3 barrels of petroleum annually depending on engine choice. The resulting carbon footprint ratings range from 10.8 to 14.1 tons of air pollution per year. The Mercedes-Benz S550 4Matic receives a national air pollution score of 6 out of 10 and a California/New England air pollution score of 7 out of 10. National and California/New England air pollution scores for the S600, S63 AMG, and S65 AMG are 6 out of 10. Strangely, the EPA does not provide national or regional air pollution scores for the rear-wheel-drive S550.