The E400 Hybrid is the gas-electric version of Mercedes' stately E-Class midsize sedan. It offers the high-tech amenities and coddling cabin that one would expect of an E-Class, but the existence of the cheaper, torquier and only fractionally less efficient E350 BlueTEC diesel limits its overall appeal.
With the standard E350's 3.5-liter V6 gas engine as a starting point, the E400 Hybrid adds a brushless electric motor and a 0.8 kWh lithium ion battery that contribute an additional 27 horsepower and 184 lb-ft. of torque. Combined output is rated at 329 horsepower - enough to allow the hybrid to sprint from zero-to-60 mpg in 6.7 seconds.
A seven-speed automatic transmission plucked from the standard E350 puts power to the rear wheels, while an automatic start/stop system eliminates fuel consumption and emissions while the vehicle is at a complete stop. Meanwhile, regenerative braking captures otherwise lost energy to recharge the lithium-ion battery. Clever packaging of the hybrid components means that, unlike many other gas-electric models, the E400 Hybrid doesn't give up any cabin or trunk space relative to its conventionally-powered siblings.
Interior practicality is important, but at their core hybrids are about fuel economy. The E400 returns 24 mpg in the city, 30 mpg on the highway and 26 mpg combined - but the less expensive E350 BlueTEC is rated at 22/32/25 city/highway/combined mpg. Given the nearly identical combined mileage figures, the E350 BlueTEC seems like the smart buy for those who don't need a hybrid badge on their luxury sedan's decklid.
Like all other E-Class models, the E400 rides on a sturdy and capable rear-wheel-drive platform. The interior is spacious and plush, with loads of wood and chrome trim along with well-organized controls.
Standard and Optional Features
Standard features on the E400 Hybrid include leatherette upholstery, a sunroof, power-adjustable front seats, an AM/FM/CD/DVD entertainment system controlled by Mercedes' COMAND infotainment system, a proximity key, dual-zone automatic climate control, Bluetooth connectivity and 17-inch alloy wheels.
Those looking to add extra luxury can opt for the Premium 1 package, which brings a navigation system with 10GB of storage space, heated and ventilated front seats, a premium sound system with an iPod/MP3 interface, a rearview camera, Sirius XM Satellite Radio, Sirius XM Traffic, Sirius XM Weather, a power rear-window shade and an active multicontour driver seat.
On top of the features included in the Premium 1 package, the Premium 2 package adds a proximity key system, an electronic trunk closer, bi-xenon headlights with active curve illumination, a headlamp cleaning system and active highbeam assist.
Giving the hybrid a sportier look is the wheel package, which includes 18-inch AMG five-spoke alloy wheels in addition to a three-spoke steering wheel.
Highlights from the numerous stand-alone options include leather upholstery, active cruise control, a panoramic sunroof, a rear seat DVD entertainment system, night view assist plus and a heated steering wheel.
In addition to ABS and ESP stability control, the E400 hybrid boasts nine supplemental restraints including two-stage front air bags, a knee air bag for the driver and pelvic air bags which work together with curtain and side air bags to provide extra protection for front occupants in dangerous side-impact collisions.
Also standard is an "ATTENTION ASSIST" system that can alert the driver to the first signs of drowsiness, a factor that causes more than 100,000 accidents a year in the U.S.A steering sensor is coupled to smart software that uses 70 parameters to establish a unique driver profile during the first 20 minutes of driving. Between 50 and 112 mph, the system identifies the erratic steering corrections drivers make as they begin to get drowsy and triggers an audible warning and a "Time for a Rest?" message with a coffee cup icon in the instrument cluster.
Optional safety equipment includes the Lane Keeping Assist system, which alerts the driver by simulating a rumble strip vibration in the steering wheel if the car drifts from its lane without the turn signals on. Part of the Lane Tracking Package, it operates at speeds above 37 mph via a system that recognizes lane markings, thanks to a small camera in the windshield and a computer that analyzes the video images.
The Lane Tracking Package also includes Blind Spot Assist, which monitors both blind spots behind and to the side of the vehicle. Whenever a turn signal is activated with a vehicle in the blind spot, the driver gets visual and audible warnings.
Gas-electric luxury sedan rivals to the E400 Hybrid include the Lexus GS 450h, the Infiniti M Hybrid and the BMW ActiveHybrid 5. Though priced at the lower end of that competitive set, the E400 Hybrid is less fuel-efficient than all but the BMW. And, of course, there's the less expensive E350 BlueTEC, which returns 32 mpg on the highway thanks to its potent oil-burning V6.