The previous Lexus GS 450h boasted V8 power with V6 fuel economy, which was certainly a worthwhile technological achievement. Most hybrid vehicle buyers care more about mpg than mph, though. That's why they expect their gasoline-electric vehicle to be much thriftier than the comparatively paltry 23 mpg EPA combined achieved by the outgoing GS 450h. (You can probably see where this is going.)

The completely redesigned, next-generation 2013 Lexus GS 450h returns 31 mpg EPA combined thanks to improvements made to both the gasoline-powered engine and the electric motors. Forget V6 fuel economy; that's equal to the humble Mini Cooper. More impressively, this efficiency has not been achieved by making the GS 450h a Prius-like slug. It might be a wee bit slower and less powerful than before, but it can still accelerate quicker than the regular GS 350 and also comes close to V8-powered luxury sedans.

Fuel efficiency isn't the only improvement for the 2013 GS 450h, however. The radically redesigned styling inside and out is the most obvious change, and we think it transforms the GS from forgettable to eye-catching. Length and wheelbase remain the same, but the chassis is pulled out wider by about 2 inches. An improved rear suspension design and a redesigned battery pack allow for more trunk space, which was a sore spot in the old GS.

There are significant mechanical changes, too. Revised suspension geometry, a stiffer body structure and a quicker steering system help make the GS the best-handling Lexus this side of the IS F or LFA. Yes, even in hybrid form. In fact, the Adaptive Variable Suspension that's optional on the GS 350 is standard here, improving both ride and handling.

Besides the cabin's modern new look, interior designers imposed a diet on various components, shaving pounds to keep weight down even as they also added a slew of new features like the Remote Touch infotainment system and sport seats with multiple adjustments. Longtime Lexus buyers needn't worry about quality either, as the GS maintains the brand's reputation for high-quality materials and excellent build quality. The electronics controls are more complicated this year, though.

In total, the 2013 Lexus GS 450h is a vastly more appealing car than the outgoing model. It's both a better hybrid and a better luxury sedan. However, despite its more fuel-efficient powertrain, a GS hybrid is still a dubious decision if it's made strictly to save money. When similarly equipped, a new 450h costs about $11,500 more than the similarly new 350. According to EPA fuel economy estimates, you'd have to own the 450h 19 years in order to pay off the hybrid price premium using fuel savings alone. True, that's better than the 57 years required to break even with the old car -- and you do get extra power -- but that's still a big chunk of change.

If you're interested in more than simply reducing your consumption of gasoline, then the GS 450h is one of the best luxury sedans available in which to do so. We still recommend checking out the cheaper Infiniti M35h and diesel-powered Mercedes-Benz E350 Bluetec, but neither can quite match that impressive 31 mpg of the GS.

The 2013 Lexus GS 450h is the hybrid version of the regular GS 350 sedan, which is reviewed separately. There is only one body style and trim level available.

Standard equipment includes 17-inch wheels, an adaptive suspension, adjustable drive settings, automatic and adaptive LED headlights, LED running lights, heated and auto-dimming mirrors, automatic wipers, a sunroof and keyless ignition/entry. Inside the cabin you get cruise control, "S-flow" automatic climate control (focuses air only to occupied seats), heated and ventilated eight-way power front seats with lumbar adjustment, driver memory functions, leather upholstery, a heated power-adjustable tilt-and-telescoping steering wheel and a power rear sunshade. Electronic features include Bluetooth phone connectivity, text-to-speech text messaging, the Safety Connect emergency communications service and a 12-speaker surround-sound audio system with a six-CD changer, satellite radio, an auxiliary audio jack and an iPod/USB audio interface.

The optional navigation system brings with it a larger central display screen, Bluetooth phonebook downloading capability, voice controls, real-time traffic and other information, and the Enform suite of smartphone app features. The Luxury package adds 18-inch wheels, additional front seat adjustments, passenger memory functions, rear climate and audio controls, manual rear side sunshades and upgraded leather upholstery. The Luxury package can also be had with heated rear seats and a night vision camera system.

Stand-alone options include different 18-inch wheels, a rearview camera, an automated parallel parking system, an active lane-departure prevention system, adaptive cruise control and a pre-collision warning system, blind-spot monitoring and a head-up display.

Powering the 2013 Lexus GS 450h are a 3.5-liter gasoline V6 and a pair of electric motors. A total system output of 338 horsepower is sent to the rear wheels through a specialized continuously variable automatic transmission (CVT).

Lexus estimates that the GS 450h will go from zero to 60 mph in 5.6 seconds, a swift performance that slots in between six-cylinder and V8 midsize luxury sedans. EPA-estimated fuel economy is 29 mpg city/34 mpg highway and 31 mpg combined.

Every 2013 Lexus GS 450h comes standard with antilock brakes, traction and stability control, front and rear side airbags, side curtain airbags and front knee airbags. Also standard is the Lexus Safety Connect system, which includes automatic collision notification, an emergency assist button and stolen vehicle location services.

Optional features include a rearview camera, a night vision system, blind-spot monitoring and a lane-departure warning system that can steer you back into place should you fail to act. Adding the optional adaptive cruise control includes a pre-collision system that detects impending collisions and responds by pre-tensioning the seatbelts and activating brake assist.

As a luxury hybrid, the 2013 Lexus GS 450h goes about its business silently and efficiently, wrapping its occupants in a cocoon of serenity. If that's all you're expecting, then the GS delivers. However, it can provide a lot more than that. That hybrid powertrain may be efficient, but it also boasts surprisingly swift acceleration.

The adaptive variable suspension that's optional on the regular GS 350 is standard on the hybrid, and constantly adapts to road and driving conditions to provide the best ride and handling possible. The system is driver-adjustable to include Eco, Normal, Sport and Sport Plus settings, and besides the suspension, it also controls steering effort, throttle response and stability control intervention. Just want that silent and efficient commute? Stick with Eco or Normal. Feeling feisty or want to show your BMW-owning buddy that hybrids can have some fun, too? Dial up Sport Plus.

Complementing its physical and dynamic makeover, the 2013 Lexus GS line also gets a revised cabin. In the best Lexus tradition, it's a finely crafted interior marked by soft leather and rich wood and aluminum trim. Befitting this caliber of luxury sport sedan are seats that are firm and cosseting in equal measure, and limited only by the degree of power adjustments you choose.

The cabin also offers more space, with slightly more head- and shoulder room. The front seat has been lowered, meaning you now feel like you're sitting in the GS, not on it, and taller drivers won't find their hair  grazing the roof. Rear seat passengers will also appreciate nearly 3 inches more hiproom compared to the previous model. Trunk space is also improved, as the battery pack has been repackaged to salvage an extra 3 cubic feet of space. Total cargo volume of 13.2 cubes isn't great for a midsize sedan, but it's better than many hybrid sedans can provide.

The Remote Touch multimedia controller -- a mouselike device that allows the user to move among a variety of icons on a large centrally located screen-- has also been revised. It's a nifty technological achievement, but in practice, we've found it can draw your eyes away from the road for too long. We recommend trying it out thoroughly on a test-drive.