For more than 20 years, the Mercedes-Benz E-Class has been one of the most successful midsize luxury sedans. For many, it represents the ideal middle ground between what could be seen as the plebian C-Class and the overly visible and expensive S-Class. The current-generation E-Class, introduced for the 2003 model year, has also been a successful one, and we've been impressed with its dignified presence, top-notch refinement and all-around capabilities.

For 2009, the Mercedes-Benz E-Class pretty much stands pat. As before, it's offered as a sedan or a wagon and with four different engine choices. While the Mercedes E350 and E550 have been the most popular models in years past, recent demand for better fuel efficiency just might turn buyers' attention to the E320 Bluetec -- it is, after all, the only midsize luxury sedan in the U.S. powered by a diesel-fueled engine. Shedding the stigma associated with diesel-powered cars, this V6 engine has a special urea additive that makes it run much cleaner than those old Mercedes-Benz diesels. On the other end of the spectrum, the E63 AMG's 507-horsepower V8 offers wicked speed and performance -- it goes from zero to 60 mph in just 4.3 seconds, quicker than most sports cars.

The E-Class ranks very highly among its competitors even though it's generally the most expensive of the bunch. The Audi A6, BMW 5 Series, Cadillac CTS, Infiniti M35/M45, Jaguar XF and Lexus GS also offer class-worthy power, handling and feature content for less coin. Meanwhile, the E63 AMG has some serious competition in the form of its arch-rival, the BMW M5, as well as Cadillac's new-for-'09 upstart, the 556-hp CTS-V, which is expected to undercut both models by tens of thousands of dollars.

In all honesty, you're not going to go wrong with any of these cars. As a sport-themed luxury sedan, the E-Class probably isn't the best choice. But for a luxury car that blends an intoxicating mix of luxury, brand cachet and performance, the E-Class is worth every penny.

The 2009 Mercedes-Benz E-Class is available in both sedan and wagon body styles. Trim levels include the E320 Bluetec (sedan only), E350 (sedan and wagon), E550 (sedan only) and the high-performance E63 AMG (sedan and wagon). The E350 and E550 are available with 4Matic all-wheel drive.

The E320 Bluetec comes standard with 16-inch wheels, a sunroof, 10-way power front seats with memory settings, dual-zone automatic climate control, a power tilt/telescoping steering column, the COMAND interface and a Harman Kardon surround-sound audio system with an in-dash six-CD/DVD changer and an auxiliary audio jack. The E350 sedan and wagon are equipped similarly. The E350 sedan can also be equipped with a no-cost Sport Package that includes 18-inch wheels, sport front and rear bumpers, a dual chrome exhaust and a sport steering wheel with paddle shifters. E350 wagons have a power liftgate and a rear-facing two-passenger third-row seat that folds flat. The E550 sedan includes the Sport Package and a semi-active air suspension, leather upholstery and four-zone automatic climate control.

Options for the non-AMG E-Class models are grouped into two packages. The Premium 1 Package adds an iPod interface in the glovebox, heated front seats, satellite radio, HD radio and a new hard-drive-based navigation system that includes 4GB of storage for music. The Premium 2 Package includes all that plus bi-xenon headlights and keyless ignition/entry. Stand-alone options include a panorama sunroof, park assist and, for the sedan, an electronic trunk closer and split-folding rear seats.

The E63 AMG comes equipped similarly to the E550, but adds split-folding rear seats, heated front seats, satellite radio and an array of AMG performance and styling features. An AMG Performance Package exclusive to this model includes distinctive 18-inch alloy wheels, a specially tuned semi-active air suspension, a limited-slip differential and an increased top speed of 186 mph. Heated/ventilated front seats and adaptive cruise control are exclusive optional features for the E63 AMG.

The E350 is powered by a 3.5-liter V6 that produces 268 hp and 258 pound-feet of torque. The sedan is available with either rear-wheel drive or 4Matic AWD. The wagon is AWD only. The E350 is relatively quick considering its hefty weight; the sedan achieves a 0-60 sprint in the mid-6-second range. The E550 is also available in either rear-wheel drive or AWD and uses a 5.5-liter V8 that makes 382 hp and 391 lb-ft of torque. In performance testing, the E550 went from zero to 60 mph in a quick 5.2 seconds. The E320 Bluetec features a 3.0-liter turbodiesel V6 that makes 210 hp and 400 lb-ft of torque. This engine gets the E320 from zero to 60 in 6.8 seconds. All rear-wheel-drive E-Class models come with a seven-speed automatic transmission, while the 4Matic models use a five-speed automatic.

The E63 AMG is a high-performance model powered by a 6.2-liter V8 that makes 507 hp and 465 lb-ft of torque. It's mated to a seven-speed Speedshift transmission, which can change gears 50 percent faster than transmissions in other E-Class models. In performance testing, the E63 went from zero to 60 in an impressive 4.3 seconds.

Fuel economy for the 2009 Mercedes-Benz E-Class ranges widely. The EPA estimates that the rear-wheel-drive E350 gets 17 mpg city/24 mpg highway and 19 mpg in combined driving. The V8-powered E550 drops those numbers to 15/22/17 mpg. Topping both of these is the E320 Bluetec with 23 mpg city/32 mpg highway and 26 mpg combined ratings. Not surprisingly, the E63 AMG is on the low end of the fuel-economy spectrum with 12/19/15 mpg ratings.

All 2009 Mercedes-Benz E-Class models come with stability control, antilock brakes with brake assist, front and rear side airbags, full-length side curtain airbags and the TeleAid emergency system. Also standard is PreSafe, which anticipates an imminent crash and automatically takes measures to better secure occupants.

In government crash tests, the E-Class sedan earned four stars (out of five) for frontal-impact protection and a perfect five stars for side-impact protection. In Insurance Institute for Highway Safety frontal-offset crash testing, the E-Class earned the top rating of "Good."

Although power and handling are both adequate, the 2009 Mercedes-Benz E-Class doesn't seem to have the balance and tossability of the BMW 5 Series or Jaguar XF. Its straight-line performance is respectable, but when pushed hard in the corners, the E-Class displays noticeable body roll and the brake pedal's soft feel doesn't inspire confidence. As such, the E-Class is best suited for cruising city streets or taking long road trips. Aside from the powerful E63 AMG, the E320 Bluetec might just be the best bet of the bunch, as it offers acceleration times similar to its gasoline E350 counterpart, but with much better fuel economy and lots of torque, both thanks to the diesel engine.

The two-tone cabin of the E-Class sedan gives off an elegant, airy feel. Supple seats and coordinating soft-touch surfaces are complemented by tasteful wood inlays, chrome accents and gathered sections of leather on the door panels. The attractive instrumentation is generally easy to read, but Mercedes' COMAND interface can take a while to figure out.

The rear seat, while not overwhelmingly spacious, provides adequate room for two adults. In addition, the wagon has a rear-facing, two-passenger third-row seat. When this seat and the 60/40-split second-row seats are down, it provides a total of 69 cubic feet of cargo room, only a few cubes shy of the M-Class SUV's capacity.