We note the huge disparity in engine output between the S63's 518 bhp and the CDI's 235 bhp. But because of the immediacy and efficacy of the turbodiesel's torque-its almost 400 lb-ft peaks at 1600 rpm-the S320 CDI is by no means left in the dust, especially when the road begins to snake and the newly revised 4Matic all-wheel-drive system does its job. This system is now fitted with a planetary-type center differential that permanently sends 45 percent of the engine's power to the front wheels and the rest to the rear. Traction issues are met with an integrated multi-plate clutch and all the familiar electronic aids.
Both cars emanate the security, exquisite engineering and sybaritic comfort of Mercedes' flagship, and both are chock-a-block with the requisite S-Class goodies, including Mercedes' spectacular Airmatic air suspension system. Both, however, do not deliver equally outstanding fuel mileage. The S63 AMG gets around 15 mpg combined, while the S320 CDI achieves a remarkable 27. It takes the S320 longer to reach 60 mph (about 7.3 seconds) than the S63 (about 4.4 seconds), but at optimum consumption, the diesel is able to run for more than 620 miles without stopping for fuel. Remind you of a certain tortoise and hare?
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