Chevy Impala 4-Cyl. Engine Downsizing Done Well

PLYMOUTH, MI – The ’14 Chevrolet Impala, already turning heads with its expressive exterior styling, spacious interior and sturdy 6-cyl. engine, adds an all-new 2.5L 4-cyl. to its powertrain lineup sure to broaden the 55-year-old nameplate’s appeal.

Impala models with the 2.5L Ecotec engine, part of a redesigned family of stout General Motors 4-bangers, are arriving at Chevrolet dealers now.

But a new valvetrain technology sets apart this direct-injection powerplant in the Impala from previous installations in other GM models (such as Cadillac ATS), as well as a number of 5-passenger sedans from competitors also advancing the downsizing trend.

GM calls it Intake Valve Lift Control, and its inclusion on the Impala reflects how industry powertrain engineers are scouring about for the slightest uptick in efficiency to meet tightening federal fuel-economy rules and demands by consumers for bigger mileage numbers without diminished performance.

iVLC is an advanced form of variable valve timing. Unlike older engines that open and close intake valves the same way all the time, the new system varies the time intake valves remain open.

In low-lift mode, airflow into the cylinder is slightly restricted to conserve fuel during steady-state cruising, decelerating and slight acceleration.

In high-lift mode, during hard acceleration, the valves maximize airflow to deliver full power. The engine’s computer continuously determines the precise degree of valve lift, depending on driver demand.

GM considers its new approach to variable valve timing an industry first, although auto makers such as BMW and Honda employ similar technologies.

iVLC improves the Impala’s fuel economy 1 mpg (0.4 km/L), compared with a model lacking the technology. The engine, packing a potent 196 hp and 186 lb.-ft. (253 Nm) of torque, is rated at an estimated 21/31 mpg (11.2-7.6 L/100 km) city/hwy.

During a test drive here, the engine impresses, pulling the big sedan along with confidence. No one will mistake this model for its big brother with the hard-charging 302-hp V-6, but this is an entirely capable I-4.

On a mostly rural route, the Impala returns 21 mpg.

Integration with GM’s in-house 6-speed automatic transmission is outstanding, shifting smoothly and lacking the busy gear-hunting of many 4-cyl. powertrains.

The 2.5L accomplishes much without forced induction. There’s no denying the fun factor of a boosted small engine, as Ford demonstrates with its 2.0L turbocharged 4-cyl. option in the Taurus large sedan and other vehicles.

But the extra power also costs more, and dipping into the turbo too often hinders fuel efficiency.

Active noise cancellation technology, which GM uses in the audio system to knock down buzzy-ness from the little engine and booming from the torque converter, helps retain the quiet cabin of V-6 models.

The addition of active aero shutters in the front grille and underbody panels makes the 4-cyl. model more aerodynamically slippery.

Steering feel, however, does not improve with the Impala 4-cyl., despite a slight change in the hardware and sourcing from ZF instead of TRW, supplier for the V-6 model. It still seems a bit light, providing little feedback.

As is true with the V-6 model, a gated shifter would be more conducive to manually rowing through gears. The current shifter sits too far back, making it awkward to operate the tap shift buttons on each side of the lever.

Understandably, there’s only so much real estate on a center console when cupholders are a must, but it takes away from the car’s sportiness.

The 4-cyl. Impala models give away nothing in terms of styling, creature comforts or technology. The exterior design carries the same wow factor, including the smirking Camaro-like grille, and the interior is just as richly appointed and roomy as the V-6 model.

Chevy’s excellent MyLink infotainment system, which in its latest generation won top honors for car technology at the 2013 Consumer Electronics Show, also remains available with all the goodies such as natural voice recognition, 3-dimensional navigation mapping and customizable screen skins.

All ’14 Impalas also will carry GM’s newly launched free maintenance program of 24 months or 24,000 miles (39,000 km), whichever comes first.

Look for the 2.5 4-cyl. with iVLC in other GM models, starting with the redesigned-for-’14 Chevy Malibu midsize car later this year. The Impala will add a 2.4L 4-cyl. option with GM eAssist mild-hybrid technology in the coming months.

It’s unclear how many takers the Impala 4-cyl. might grab for a segment historically smitten with V-6s, but it’s a good engine with some advanced technology that gives shoppers another option on an already attractive car.

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