NAPA VALLEY, CA – For many years, Nissan Motor Co. Ltd.’s Infiniti luxury division has taken a one-dimensional approach to the Lower Luxury Car segment, as defined by Ward’s.

From Acura to Volvo, most upscale brands have played both ends of the segment, making available fuel-efficient engines – some with four cylinders – as well as high-output 6-cyl. powerplants for those 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 260 lb.-ft. (353 Nm) of torque 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 federal mandates to improve fuel economy loom large, so Infiniti has unveiled a new addition that should boost the brand’s average mpg, as well as 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) of torque.

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 is not new, and it 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 mostly rural roads here in California wine country, 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.

’11 Infiniti G25 Journey
Vehicle type Front-engine, FWD 4-door sedan
Engine 2.5L DOHC V-6 with aluminum block, heads
Power (SAE net) 218 hp @ 6,400 rpm
Torque 187 lb.-ft (254 Nm) @ 4,800 rpm
Bore x stroke (mm) 85 x 73.3
Compression ratio 10.3:1
Transmission 7-speed automatic
Wheelbase 112.2 ins. (285 cm)
Overall length 187.9 ins. (477 cm)
Overall width 69.8 ins. (177 cm)
Overall height 57.2 ins. (145 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
Pros Cons
VQ engine lineage Lacks VVT, DI
Good fuel economy Lacks brute strength
G lineup expanded What took so long?

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), perhaps because it routinely begs to be driven hard.

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, 4 valves per cylinder, liquid-filled engine mounts, 7,500-rpm redline and a closed-loop emissions feedback system with two catalysts.

The 3.7L has a slightly higher compression ratio, larger bore and longer stroke. Both engines are certified for 50-state availability at the LEV II emissions stage.

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.

Through November, G sales are up 21.6% to 51,070 units compared with like-2009, according to Ward’s data. Through the first three quarters, the G has been the third best-selling Lower Luxury nameplate, behind the BMW 3-Series and Mercedes C-Class.

With a base price of $30,950, the G25 shares the same exterior, interior and chassis as the G37 and comes standard with leather-appointed seats, Shodo aluminum interior trim, premium audio, automatic climate control, HID Xenon headlamps and Vehicle Dynamic Control.

Having been mildly refreshed for ’10, the G sedan remains one of the best-looking cars in the segment.

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

Nissan assembles the G25 at its plant in Tochigi, Japan.

tmurphy@wardsauto.com