Chevrolet Impala is a popular sedan
By Bob Plunkett, Thu, 22 Dec 2005 08:00:00 PDT
NASHVILLE, Tenn. -- Mid-morning traffic on West End Avenue near the Vanderbilt campus in Nashville flows easily as we steer toward the entry ramp of I-40 and head into the hills of Tennessee for a day of tests driving the latest iterations of Impala, Chevrolet's largest sedan. With its mid-size structure yet big-car cabin space and seats for all in the family, Impala ranks among the best-selling passenger cars in America and it's also the best-seller at Chevrolet in a nameplate tracing through five decades and accounting for more than 14 million units.It scores a substantial make-over for 2006 models.
The changes include keen new body styling, a revamped passengercompartment with premium options like leather upholstery and innovative flip-and-fold rear seats, and new trim and powertrain choices.
Two models, the entry-issue Impala LS and upscale Impala LT, tote a new 3.5-liter V6 engine with variable valve timing (VVT). Deluxe model Impala LTZ goes further with additional trim and comfort gear plus the new GM 3.9-liter VVT V6.
And a new sport-tuned variation bearing a fabled badge retrieved from Chevrolet history shows up as the Impala SS packing a big 5.3-liter V8 rigged with GM's innovative Displacement on Demand (DOD) technology to conserve on fuel.
It subsequently became a production reality in 1958 as the top Chevrolet with cool coupe or convertible styling. Other shapes followed with trendy fins and muscular shoulders, and by 1961 a special package forged the Impala Super Sport, first of the souped-up SS breed. In its heyday of the Sixties, Impala amounted to a full-size car with an iron-block V8 engine that exerted massive horsepower on the rear wheels -- but it handled like a floaty barge. By contrast, today's Impala runs about 200 inches in length with a front-wheel-drive (FWD) stance and independent suspension components to cultivate a lively personality.
It debuted in year 2000 re-oriented with FWD and a mid-size scale to replace the retired Lumina series. In Chevrolet's 2006 line, the new generation of Impala issues shows revisions for chassis and suspension systems. Impala's unit-body structure has boxed frame rails that measure wider and deeper than the previous design, as the front-end of the structure is stronger to control NVH (noise, vibration and harshness) and boost the steering and handling characteristics. Initial impression from our seat time is that Impala feels like a well-heeled and stable car with a firm ride quality and quiet isolation for the passenger compartment.
Suspension architecture was designed to deliver a refined ride, although we find the sedan also feels agile when steered through a twisty set of curves and it holds body roll to a minimum. The independent suspension has a MacPherson strut coil-over-spring unit up front with constant-rate springs and a tri-link coil-over-spring design in the rear with variable-rate springs. Power-assisted rack and pinion steering shows up on all trims with a quick 13.3:1 steering ratio. Disc brakes for all four wheels also apply.
Additional hardware for Impala LT, LTZ and SS includes an anti-lock brake system (ABS) with electronic brake force distribution (EBD) and a traction control system (TCS). Frontal air bags for front-seat riders are stock on all trims, with curtain-style air bags concealed above front and rear side windows. Impala's primary engine is the new 3500 series V6 from GM sized at 3.5 liters off an iron block with offset cylinder bores, aluminum heads and the VVT valvetrain.
Output reaches to 211 hp at 5900 rpm and the torque climbs to 214 lb-ft at 4000 rpm, with fuel economy figures of 21 mpg in town and 31 mpg for highway cruising. The plant ties to GM's electronic automatic four-speed Hydra-Matic 4T65-E transmission, a smooth and quiet shifter. A larger and stronger variation of the base engine is the 3900 series 3.9-liter V6, which is optional on Impala LT but standard for LTZ. It produces 242 hp at 6000 rpm with torque tuned to 242 lb-ft at 4400 rpm.
Fuel scores are 19 mpg city and 27 mpg highway. Core component for the new SS edition of Impala is a 5.3-liter aluminum V8 engine. The overhead-valve V8, with high-flow cylinder heads similar to those found in the 6.0-liter LS2 V8 of Corvette, delivers 303 hp at 5600 rpm and big-time torque of 323 lb-ft at 4400 rpm.
The engine's DOD wizardry automatically -- and seamlessly -- pares the number of cylinders engaged in the combustion process when boosted power is not needed. For a V8 it means cutting back to a four-cylinder mode under light-load situations in a process which improves fuel economy numbers by as much as eight percent.
Impala SS's fuel economy numbers come in at 18/28 mpg city/highway. Styling for Impala looks clean and refined in the less-is-more school of design. The slinky body features a tapered prow marked by a narrow grille and flanking corner-wrapped headlamps. Below the grille a body-colored fascia contains the air intake port and corner foglamps.
A canted hood incorporates striking curves from the headlamps and draws them in taut lines rearward to the base of a raked windshield. Sides reveal smoothly rolled shoulders and round wheelwell arches with body-colored molding streaking across the double doors. And the line of the roof is a smooth arch that tapers to a curt tail. Layout for the cabin sets a pair of sport bucket seats up front and a bench for three in back.Backs of the rear bench, split into two sections of 60/40 percent, fold down flat but the seat bottoms also tip forward against backs of front seats and expose a storage compartment underneath that's four inches deep.
Chevrolet establishes four tiers for prices, beginning at $21,330 for Impala LS and rising to $27,130 for the SS.