I wonder if this is a HEMI engine. Maybe not but it sure sounds and acts like it. Here is an excerpt:

More speed from less torque and more gears
By Greg N. Brown Email
Date posted: 05-17-2006



A faster, less torquey solution
As Inside Line has noted in its review of the ML63 AMG, the new 6.2 is a marvel of an engine. It's lighter, more powerful, cleaner, just as fuel-efficient and, arguably, more durable than the 5.5 it replaces. It's also the first engine in a Mercedes-Benz passenger car to be developed completely by AMG, which fully exercised its motorsport expertise when developing the V8's unique architecture.

In its state of tune for U.S.-bound E63 sedans and wagons, the 6,208cc four-valve DOHC V8 puts out 507 horsepower at 6,800 rpm compared to the E55's 5,439cc three-valve SOHC supercharged V8's rating of 469 hp at 6,100 rpm. Well and good. The newer car should be more powerful. Torque? The bigger V8 twists out 465 pound-feet of torque at 5,200 rpm compared to the (what's this?) 516 lb-ft of torque from the outgoing V8. The E55's torque also peaked earlier, at 2,650 rpm. Sounds like a step backward.

However, there was good reason for the reduction in torque. This allowed Mercedes to fit its new, sophisticated seven-speed automatic in place of the old five-speed. Though the new gearbox is far more efficient than the five-speed, and though it was not built to handle the massive torque of the supercharged engine, its limit of 542 lb-ft, say Mercedes engineers, gives it the required durability to handle the 6.2's far-from-paltry crank twist.

Even better, the loss of torque has had no impact on the car's performance. Let's turn to the factory for this conclusion, which says the 6.2 can launch the E63 sedan from zero to 60 mph in 4.3 seconds. (That's a worthy accomplishment for a 4,035-pound four-door — and it's also probably a conservative figure. Certainly the 514-hp European-spec car we drove in Germany felt much quicker.) To compare, the E55, according to factory numbers, takes 4.5 seconds to achieve the same speed. Race is over; the E63 is quicker. (Just to save you the trouble of looking it up, the similarly sized BMW M5 makes the dash from zero to 60 in 4.5 seconds.) Credit the E63's more efficient seven-speed transmission, improved aerodynamics and, surprisingly in this day of the bloated automobile, a moderate overall weight gain of just 45 pounds compared to the E55 sedan.