2004–2009 Chevrolet Impala SS: W-Body V8 & Supercharged V6

2004–2009 Chevrolet Impala SS — The W-Body Outlier with Boost and a V8

Historical Context and Development Background

Within the broader Chevrolet Impala family, the 2004–2009 Impala SS represents the fourth era in the nameplate’s modern revival on GM’s W-body platform. It arrived in two distinct mechanical chapters. Model years 2004–2005 revived the SS badge with the L67 supercharged 3.8-liter V6, a torque-rich solution already proven in several GM sedans and coupes. A comprehensive redesign for 2006 brought the LS4 5.3-liter small-block V8 to the same front-drive architecture, creating an unusual proposition: a transverse V8 performance sedan in an era trending toward rear-drive competitors.

Corporate strategy prioritized leveraging existing W-body tooling while delivering an SS halo to maintain showroom draw. The 2006 facelift sharpened the exterior, revised the cabin, and reconfigured powertrains across the range; the SS gained Displacement on Demand (Active Fuel Management) on its LS4 for improved fuel efficiency during light loads. While the platform’s roots traced back to the 1990s, GM developed unique engine packaging solutions for the LS4—including a shortened crankshaft, compact accessory drive, and tailored mounts—to fit a small-block V8 in a transverse layout.

On the motorsport side, the Impala name returned to NASCAR stock car branding later in the decade, giving the road-going sedan halo visibility on Sundays. On the street, the Impala SS shared market space with the Dodge Charger and Chrysler 300 (both rear-drive or AWD, HEMI available), Pontiac Grand Prix GXP (LS4 mechanical cousin), and higher-trim Toyota Avalon and Acura TL variants. Against this set, the Impala SS’s appeal was a uniquely American blend of torque, space, and understated looks—more sleeper than sport sedan, but with authentic muscle under the hood.

Engine and Technical Specifications

The SS story in this era is split between boost and cubes. The 2004–2005 SS used the Eaton-supercharged 3800 Series II L67 V6, while the 2006–2009 SS moved to the LS4 5.3-liter V8 with cylinder deactivation. Both drove the front wheels through GM’s 4T65-E HD four-speed automatic.

Driving Experience and Handling Dynamics

The supercharged V6 cars (2004–2005) deliver a punchy midrange with the familiar L67 whine. Throttle response is immediate off-idle, and the 4T65-E HD’s gearing keeps the blower on boil in typical commuting and backroad driving. Steering feel is light with modest feedback; body control is secure but tuned for everyday compliance rather than razor-edged response.

The LS4 V8 SS (2006–2009) is a different character: more effortless speed, broader torque, and a relaxed charisma at highway pace when the V8 seamlessly drops to four cylinders under light load. Stand on it and the car tugs at the wheel—torque steer is part of the experience—but the front end bites better than the spec sheet suggests, aided by SS-specific suspension tuning, 18-inch wheels, and performance-compound tires. The ride remains supple, a deliberate choice to suit long-mile duties. Braking is confident for the era with ABS standard, and heat management is acceptable for spirited street use.

Both iterations share the W-body’s strengths: straightforward controls, generous cabin space, and long-distance comfort. Neither disguises its front-drive roots on a challenging road, but both reward with accessible pace and low drama. The V8’s soundtrack and effortless surge arguably make it the more memorable mile-eater, while the supercharged V6 counters with lighter nose weight and a more eager initial turn-in.

Full Performance Specifications

Variant Breakdown (Trims, Visual Cues, Market Notes)

Ownership Notes: Maintenance, Parts, and Restoration

• Engine reliability (L67): The supercharged 3800 Series II is robust. Common service items include supercharger coupler wear (rattle at idle), idler/tensioner bearings, lower intake manifold gaskets on high-mile cars, and typical W-body coolant elbow/pipe issues. Keep fresh belts and quality coolant to preserve longevity.
• Engine reliability (LS4): Watch for Active Fuel Management lifter issues, oil consumption on neglected service, and accessory-drive wear unique to the compact LS4 package. Regular oil changes and high-quality filters help AFM lifter longevity.
• Transmission (4T65-E HD): Known for pressure control solenoid wear, 4th clutch hub spline wear on high-mile units, and valve body varnish when fluid is never serviced. Proactive fluid/filter service can materially extend life.
• Chassis and ancillaries: Front wheel bearings, intermediate steering shaft clunk, rear suspension bushings, and HVAC blend door actuators are familiar W-body maintenance points. Inspect rocker panels and rear wheel arch areas for corrosion in salted climates.
• Service intervals: Period GM schedules pair the oil life monitor with conventional/long-life oils; iridium spark plugs typically specified around the 100,000-mile mark; Dex-Cool coolant commonly specified for extended intervals when tested and maintained; transmission service prudent in severe use despite long-life claims.
• Parts availability: Excellent mechanical and electrical parts availability thanks to GM volume. Trim-specific SS items (wheels, interior fabrics, unique badges) are findable but condition-sensitive; buy the best you can.
• Restoration difficulty: Straightforward mechanically; electrical diagnostics and quality suspension refreshes separate average from excellent examples. Preserving original paint/trim and exhaust tips helps value.

Cultural Relevance and Enthusiast Perspective

The 2004–2005 supercharged SS revived the idea of a torque-rich Impala with understated styling, while the 2006–2009 LS4 SS stands as one of the very few modern mass-produced, front-drive V8 sedans from Detroit. That novelty—combined with sleeper aesthetics—gives the car a niche following. The Impala moniker’s presence in stock car racing later in the decade provided a visibility halo, even if the racing shells shared little with showroom metal. Values for clean, unmodified examples tend to reflect condition and mileage rather than rarity, with low-mile cars appealing to collectors who appreciate GM’s unconventional engineering choice.

FAQs

• Is the 2006–2009 Impala SS really a V8? Yes. It uses the LS4 5.3-liter small-block V8 with Active Fuel Management, driving the front wheels through a 4-speed automatic.
• How quick is the LS4 Impala SS? Period instrumented testing commonly recorded 0–60 mph in the mid-to-high-5-second range and quarter-miles in the low-14s.
• What about the 2004–2005 supercharged SS? The L67 3.8-liter supercharged V6 typically produced mid-6-second 0–60 mph performance and quarter-miles around 15 seconds.
• Known problems to check before buying? On LS4 cars, listen for valvetrain tick and watch for oil consumption; on L67 cars, check for supercharger coupler noise and intake/coolant seepage. All years: assess transmission shift quality, wheel bearings, steering shaft clunk, and HVAC blend door operation.
• Is torque steer severe? Under hard throttle, especially on the LS4 V8, torque steer is noticeable. Tire choice and alignment condition have a significant effect.
• Does cylinder deactivation cause issues? It can if oil changes are neglected. Using the correct oil specification and reasonable service intervals helps maintain AFM lifter health.
• Brake and suspension upgrades? OE-quality pads/rotors and fresh bushings significantly improve feel. Many owners opt for performance tires on the SS’s 18-inch wheels for a tangible grip and braking benefit.
• Collector outlook? The niche FWD V8 layout, last-of-line SS status for this W-body Impala, and the blower-era cars’ character give both versions a modest cult following. Unmodified, low-mile examples are the most desirable.