Across the entire family of E Class models there are four engines; and of those, two are all-new for 2012.
Base E350 models include a completely new 3.5-liter direct-injection V-6, making 302 horsepower, while E550 models get a new 4.6-liter direct-injection V-8 that makes 402 horsepower. A 210-horsepower, 3.0-liter turbo-diesel V-6 is included in BlueTec models. And at the top of the line, performance-oriented E63 AMG models get a 518-hp, 5.5-liter biturbo V-8 built by in-house tuner AMG.
If you want the diesel, it's only offered in the Sedan (in Luxury or Sport guise, though). Both the V-6 and V-8 gasoline engines are available in the Sedan, Coupe, and Convertible, while the Wagon only offers the 3.5-liter V-6, but adds standard 4Matic all-wheel drive. The special E63 AMG is rear-wheel drive only.
4Matic all-wheel drive is also optional on much of the Sedan range (E350 and E550 models), and later in model year 2012 it's offered in Coupes for the first time.
At the time of posting, we still hadn't driven any of the E Class sedan models with the all-new V-6 or V-8 engine; but we have driven other Mercedes-Benz models with the V-6, and it's a significant improvement over the previous engine in smoothness, with a strong powerband all the way up to redline and plenty of torque down low. The diesel remains the green choice of the bunch, and one of our editors' picks; it's rated at 24/34 mpg city/highway.
All standard E Class variants come standard with a seven-speed automatic transmission, and driver-adjustable suspensions. An air-shock system provides a range of comfort to sport ride quality for the V-8 models, while V-6s use a mechanical valve control to produce a similar range of adjustment. Driving dynamics are controlled and agile for the car's size, though tuning isn't as taut as the sportier end of BMW's or Audi's ranges until you step up to the factory-tuned AMG car.
The high-performance E63 AMG gets a special version of the seven-speed automatic transmission that swaps in a wet-plate clutch for the torque converter, but keeps the usual planetary gear arrangement. The result is quicker shifts, more direct engagement with the engine, and higher performance.