The plug-in hybrid Mercedes-Benz S550e is world-class in every way. It’s also environmentally friendly with its efficient powertrain, which integrates a twin-turbocharged V-6 engine and an electric motor with a seven-speed 7G-TRONIC automatic transmission. The combination provides premium sedan buyers a luxury driving and ownership experience with the benefit of 14 miles of zero-emission electric driving. Overall driving range provided by the S550e’s 141 horsepower electric motor and 329 horsepower 3.0-liter V-6 is a total of 450 miles.

An array of advanced technologies optimize engine performance while reducing emissions, fuel consumption, and noise. These include rapid-multispark ignition that can fire up to four times-per-millisecond, high-pressure direct injection that can fine-tune fuel spray in 0.1 millisecond, a lightweight die-cast alloy block, widely variable valve timing, reduced friction, and on-demand ancillary components that de-activate when unneeded. An E-Boost feature enables the electric motor to raise total torque up to 479 lb-ft for quick 0 to 60 mph acceleration in just 5.2 seconds. The S550e has remarkable efficiency of up to 63 MPGe (miles per gallon equivalent) on the highway while driving on battery power. A drag coefficient of 0.27 CD contributes toward energy savings.

Four drive modes can be selected: The intelligent Hybrid mode optimizes use of the gasoline and electric motors together based on conditions and terrain, and even uses navigation data about the route. All-electric E-Mode offers emission-free driving around town. E-Save conserves battery power on longer highway trips and allows all-electric driving as desired in urban areas. Charge mode maximizes battery replenishment.

Economy and Sport programs vary the car's performance character while favoring electric or gasoline power. A third Economy+ program activates accelerator pedal tactile feedback that aids more efficient driving. Whenever it’s possible to save fuel by coasting, a double pulse in the pedal encourages lifting off the accelerator. When using all-electric E-Mode, pushing the pedal beyond a distinct pressure point engages the gas engine for an instant boost of power.

Advanced driver assist systems are prevalent in the S550e. These include Distronic Plus with steering assist, BAS Plus with cross-traffic assist, pre-safe brake with pedestrian recognition, blind spot assist, active lane keeping, and speed limit assist. The S550e also features enhanced radar-based regenerative braking. The extremely well-appointed cabin features dual 12.3 inch high resolution screens for driver instrumentation and a center display.

With its sleek styling, refined and accommodating interior, and plethora of advanced on-board electronics, BMW’s $96,600 S550e gives luxury sedan buyers yet another reason to opt for an environmentally-positive plug-in hybrid.

It’s been clear from our first week behind the wheel of our long-term 2012 Kia Optima Hybrid that this car is destined to be a family favorite. That initial impression hasn’t faded as the miles roll by. This car simply does everything well while delivering exceptional fuel economy.

How exceptional? The EPA rates the Optima Hybrid at 35 mpg in the city and 40 mpg on the highway. We have actually been doing better than that with a combined average hovering around 40 mpg. The Optima hybrid responds well to efficient driving techniques. With a light touch on the accelerator, we’ve been able to push highway mileage up into the mid-40 mpg range. Add to those numbers a 17.2 gallon fuel tank and you have a cross country cruiser with very long legs.

One of the keys to this great fuel economy is the hybrid system’s ability to operate in pure electric mode at speeds up to 62 mph. It’s quite impressive to tip out of the throttle slightly at freeway speeds and watch the energy gauge drop into the EV zone as the gasoline engine shuts down. Kia is using an advanced technology 270 volt lithium-polymer battery in the Optima Hybrid.

According to Kia, it takes up 40 percent less space, is 20-30 percent lighter, and 10 percent more efficient than comparable nickel-metal-hydride battery packs. Impressively, it offers twice the power density and will hold a charge 25 percent longer, while weighing only 95 pounds. Kia is backing the battery with a 10-year/100,000 mile warranty.

The Optima Hybrid’s 2.4-liter, Atkinson cycle four-cylinder gasoline engine produces 166 horsepower. It is coupled via a wet clutch to Kia’s Interior Permanent Magnet synchronous electric motor that kicks in another 40 horsepower and 151 lb-ft of torque. That’s enough punch to accelerate from 0-60 mph in 8.3 seconds. We also appreciate the six speed automatic transmission that delivers more positive throttle response than the CVTs commonly used in hybrids.

One of the pleasant surprises we’ve experienced is the constant string of compliments we receive on the Optima Hybrid’s styling. Kia worked on the hybrid variant’s aerodynamic styling to bring its coefficient of drag down to an impressive 0.26 Cd. That’s extremely low for this size car and a 10 percent improvement over the standard Optima. It also rides a bit lower and, with its 17 inch alloy wheels and 55-series low rolling resistance tires filling up the wheel wells, has a stance more like that of a performance sedan than a fuel-sipping hybrid. The Kia Optima Hybrid is a family sedan that is fun to drive, economical, versatile, and stylish.