For years, Nissan Motor co. ltd.'S Infiniti luxury division has taken a one-dimensional approach to the Lower Luxury segment, as defined by Ward's.

From Acura to Volvo, most upscale brands have played both ends of the sector, making available fuel-efficient engines as well as high-output powerplants for customers wanting more.

Infiniti has been the exception, positioning its stylish G at the upper end of the performance range.

In 2004, for instance, Infiniti was one of only two luxury brands (Acura was the other) with premium V-6s knocking on the door of 300 hp. At the time, Nissan's 3.5L VQ V-6 produced 298 hp and was the envy of the powertrain world, on its way to a 14-year run on Ward's 10 Best Engines list.

What followed was a generation of smooth and powerful direct-injection 6-cyl. gasoline engines from various luxury auto makers eager to match — and in some cases surpass — the VQ's capabilities.

But U.S. mandates to improve mileage loom large, so Infiniti has unveiled a new addition that should boost the brand's average mpg — and its bottom line.

The G25 sedan, now on sale, joins the G37 sedan, coupe and convertible in the lineup. While the latest 3.7L VQ in the G37 produces 328 hp and 269 lb.-ft. (365 Nm) of torque, the G25 makes do nicely with a smaller 2.5L version of the VQ (code name VQ25VHR) that generates 218 hp and 187 lb.-ft. (254 Nm).

This 2.5L V-6 carries over from the Japanese market, where it has been available in the Nissan Skyline since 2002. True, the engine lacks certain technologies (such as direct injection and variable valve-timing) that have become the price of entry for most luxury engines.

But the smaller V-6 has an excellent lineage and carries on the hallmarks of the VQ family: razor-sharp throttle response, supreme balance, top-notch NVH, potent midrange and an unmatched willingness to rev.

On rural roads in northern California, the G25 is right at home, cruising effortlessly and sounding relaxed, due to an exhaust system tuned for comfort rather than high-strung performance.

Acceleration is adequate for passing, although the 7-speed automatic transmission with Downshift Rev Matching better handles bursts of power in automatic mode than when self-shifting. There is no 3-pedal manual transmission in the G25.

As a fuel-economy play, the G25 is compelling, delivering 30 mpg (7.8 L/100 km) during a 35-mile (56 km) loop in light traffic.

That type of mileage is noteworthy because the 3.7L VQ generally averages below 20-mpg (11.7 L/100 km).

The G37 Sport, with 6-speed manual, is rated by the Environmental Protection Agency at 17/25 mpg (13.8-10 L/100 km) in city/highway driving. Meanwhile, the G25 is rated at 20/29 mpg (11.8-8.1 L/100 km), although the all-wheel-drive variant suffers a slight penalty.

The VQ is a modular engine family, and both the 2.5L and 3.7L versions share many similar features: aluminum-alloy blocks and heads, resin-coated pistons and a closed-loop emissions feedback system with two catalysts.

Far and away, the G is Infiniti's best-selling nameplate and will remain so with the arrival of the G25. With a few months in the marketplace already, Infiniti says the vehicle is performing as expected, making up about 30% of the G's mix.

With the G25, Infiniti can take on fuel-efficient rivals such as the Lexus IS 250, Acura TSX and BMW 328i.

'11 Infiniti G25 Journey

Vehicle type: Front-engine, FWD 4-door sedan

Engine: 2.5L DOHC V-6 with aluminum block, heads

Power: 218 hp @ 6,400 rpm

Torque: 187 lb.-ft (254 Nm) @ 4,800 rpm

Bore × stroke (mm): 85 × 73.3

Compression ratio: 10.3:1

Transmission: 7-speed automatic

Wheelbase: 112.2 ins. (285 cm)

Curb weight: 3,552 lbs. (1,611 kg)

Base price: $32,350

Fuel economy: 20/29 mpg (11.7-8.1 L/100 km)

Competition: Acura TSX, BMW 328i, Lexus IS 250, Mercedes C300, Saab 9-3