When you think of green cars, the usual image is likely an eco-friendly commuter pod that gets you on the right side of the karma equation. While the 2012 Lexus LS 600h L is indeed a hybrid vehicle, it shouldn't be considered green -- unless you count the green in your wallet that it'll deplete, that is. With an MSRP about $40,000 more than a conventional LS 460 L and a fuel economy advantage of just 1 mpg EPA combined, it would take the average driver almost 300 years to recoup the added purchase cost with fuel savings.

In Lexus' defense, it positions the LS 600h L as a car able to deliver performance comparable to V12-powered luxury sedans while returning fuel economy like a V8-powered car. But in Edmunds testing, this LS hybrid accelerates more slowly than not only its 12-cylinder rivals but also the conventional LS V8.

Certainly, the LS 600h L delivers the exceptionally luxurious interior and crypt-quiet silence for which Lexus has always been noted. But overall, we suggest looking into the few other competing vehicles on the market. The Mercedes-Benz S400 Hybrid, Mercedes-Benz S350 Bluetec diesel and Porsche Panamera Hybrid all return better gas mileage at an MSRP that is cheaper. To a lesser degree, the BMW 7 Series ActiveHybrid may be of interest as well. In the end, the Lexus LS 600h L might have been the first hybrid-powered prestige sedan, but times have changed and it is no longer the best.

Classified as a full-size hybrid luxury sedan, the 2012 Lexus LS 600h L is essentially a long-wheelbase version of the conventional LS 460. This hybrid is the most expensive model that Lexus makes in large numbers, and as such, comes fully loaded with features.

Standard features include 19-inch alloy wheels, LED projector headlights, keyless ignition and entry, power door closers, the Lexus Advanced Parking Guidance System (which automatically steers the car into a parallel parking spot), parking assist with a back-up camera, Bluetooth phone and streaming audio, a hard-drive-based navigation system (with real-time traffic and weather and USB/iPod connectivity), leather-trimmed seats and interior and a heated steering wheel.

Also included is a Cold Weather package (windshield de-icer and high-output heater), a 16-way power driver seat and 12-way power passenger seat (with memory for both), heated and ventilated front seats, heated rear seats, a power rear sunshade, Lexus Enform telematics and an earth-shaking 19-speaker Mark Levinson surround-sound system (with six-disc CD/DVD changer, satellite radio, a music server with a 2,000-song capacity and auxiliary/USB input jacks).

As if all that were not enough, Lexus offers a couple of option packages to further pamper occupants. Package content and availability varies from region to region. The Premium Package II includes four-zone climate control, a center console with a cooler box, power rear door shades, additional wood trim, a rear audio control panel, rear heated and cooled seats, a rear-seat entertainment system and rear-seat side airbags.

The Executive-Class Seating Package II adds a power recliner with leg rest and massage feature for the right rear seat, a fixed rear center console that eliminates the fifth seating position, a rear-seat wood table, infrared temperature sensors that adjust the climate control for the rear passengers and special 18-inch, nine-spoke wheels. In most cases, the only stand-alone option is adaptive cruise control with a pre-collision safety system.

The 2012 Lexus LS 600h L is powered by a full hybrid system made up of two electric motor/generators and a 389-horsepower 5.0-liter V8. With all motors working together, peak output is 438 hp. Power is routed to all four wheels through a specialized continuously variable transmission (CVT) that features manual shift control. The transmission also has three driver-selectable driving modes -- Normal, Power and Snow -- for changing road conditions.

Like other Toyota-built hybrid systems, the LS 600h L's powertrain can propel the car solely under electric power at low speed and for limited distances. The air-conditioning system runs off electric power, allowing the gas engine to shut down at stops. And like other related hybrid systems, this system recharges the battery pack via regenerative braking when decelerating.

In recent testing, Edmunds managed a run to 60 mph from a standstill in 6.0 seconds -- a tenth of a second slower than a gas-powered LS 460 L we tested. Equally disappointing is the fuel economy, registering an EPA-estimated 19 mpg city/23 mpg highway and 20 mpg in combined driving, which naturally isn't much different from the regular LS 460 L's 16/24/19 mpg except in the city cycle. The one bright spot concerns the hybrid's lower emissions, as it earns SULEV status. Still, the conventionally powered LS boasts a clean ULEV rating.

Standard safety features on the 2012 Lexus LS 600h L include traction and stability control, front-seat side airbags, full-length side curtain airbags, knee airbags for the front seats and Safety Connect emergency telematics. Rear-seat side airbags are included with either option package. If the LS is equipped with the optional adaptive cruise control, a pre-collision system senses impending frontal impacts and automatically pre-tensions seatbelts and boosts braking power.

In recent Edmunds brake testing, an LS 600h L came to a stop from 60 mph in 120 feet -- about average for this class. In crash testing conducted by the Insurance Institute for Highway Safety, the Lexus LS scored the highest rating of "Good" for its protection in frontal-offset impacts.

There are few cars (if any) that are as quiet as the 2012 Lexus LS 600h L. With initial power supplied from the electric motors alone, acceleration from a stop is eerily silent. The supple suspension easily absorbs any road imperfections, while the sound insulation isolates all occupants from the world outside.

If the Lexus LS has been criticized for anything, it's a lack of passion in its driving experience, and the same thing can be said for the LS 600h L. While subdued, the machinations of the hybrid system add another layer of insulation between the driver and the road. As an automotive isolation chamber, the LS 600h is among the world's best, but this is not a sport sedan by any stretch of the imagination.

In terms of sheer luxury, you'd probably have to acquire an executive jet to rival the Lexus 600h L's cabin. Most surfaces are covered in supple leather accented by rich wood trim. Adding either of the optional packages will elevate the interior to Maybach or Rolls-Royce territory for comfort and space. As with other Lexus instrument panels, the LS 600h's gauges are strikingly sharp and legible.

Unfortunately, much of the LS 600h L's trunk space is taken up by the hybrid and rear climate control components, dropping maximum luggage capacity to only 10 cubic feet, which is less than most compact car trunks.