Although Mercedes-Benz had to elevate its game as regards the exterior of the ’07 E-Class, which mostly takes the form of slight adjustments, not wholesale changes (e.g., the grille is 3-cm larger and has a more-tapered V-shape), the real story of the car is found under the hood, particularly in the guises of the E63 AMG and E320 BLUETEC versions.
The team at AMG—Mercedes’ performance division—decided the revised E-Class would be the perfect platform for them to go all out and devise the first AMG-only engine: A naturally-aspirated 507-hp, 6.3-liter V-8. Yes, the supercharged 5.5-liter engine has been cast aside for the E-Class, although those with a hankering for force-fed power can still get 5.5 under the hood of the SL55 and G55 AMG models. Utilizing the experienced gained in auto racing, the AMG team decided to get a little creative by adding a twin-wire-arc-sprayed coating in the cylinder bores, which reduces friction while providing running surfaces that are twice as hard as conventional cast iron cylinders. Construction is compromised mainly of a high-strength silicon-aluminum alloy, complete with four valves per cylinder, variable valve timing, bucket tappets used in place of traditional rocker arms and a variable intake manifold. Suffice to say, this engine doesn’t follow the off-the-shelf parts bin philosophy used at other manufacturers, as virtually no parts are shared with any member of Mercedes power train family. Engineers also had to tone down the new engines torque performance—which now stands at 465 lb-ft. at 5,200 rpm, compared with 516 lb-ft. at 2,650 rpm on the outgoing supercharged engine—to accommodate the ultra smooth 7-speed gearbox that’s become a mainstay for this latest generation of Mercedes vehicles.
While the AMG team may have pulled off a power tour de force, engineers working on the 3.2-liter BLUETEC diesel engine deserve equal kudos for their hard work. While the BLUETEC system will not be available in the U.S. until later in ‘06, after the oil industry gets its act together and produces the low-sulfur diesel needed to comply with the new technology, Mercedes has high hopes the E320 BLUETEC will build on the success of the last generation E320 CDI, which surpassed every sales target as more than 4,500 units were sold during first year of its return to the U.S. market. As U.S. emission regulations begin to strangle the potential success for diesels, Mercedes plans to introduce a new emission technology that will meet 45 state rules, while progressing along the path to 50-state compliance in the future. Mated to the latest diesel engine technology, including piezo-electric injectors and third generation direct-injection technology, BLUETEC incorporates four after-treatment units in the exhaust stream—an oxidizing catalytic converter, particulate filter, advanced “denox” storage converter, and a SCR catalytic converter, to treat nitrogen-oxide to acceptable levels.—KMK