2006 Chevrolet Impala Engine, Speed, & Interior Review

GM says the 60-degree engines are inherently smooth enough to eliminate the need for balance shafts, and we'd agree. In fact, the 3.5-liter V-6--EPA-rated at 21-mpg city/31-mpg highway and E85-capable (meaning it can run on fuel that's 85 percent ethanol)--is good enough that we wonder if the 3.9-liter is even needed. Chevy claims an 8.4-second 0-to-60-mph time for the 3.5 engine, 7.8 seconds for the 3.9, and a brisk 5.7 for the 5.3-liter V-8. The 3.5 has a single exhaust tip, while the 3.9 and 5.3 have chromed dual tips. Neither, though, has a true dual exhaust.

With a layout essentially identical to the 5.3-liter version of the 2005 Pontiac Grand Prix, the turned-sideways V-8 is a tight fit, nicely executed. Yes, there's torque steer under acceleration, but it isn't, say, Saab Viggen torque steer. The V-8 has displacement on demand, and it's moderately seamless. You can feel something happening, but it's hard to tell if it's the four cylinders leaving or rejoining the party or the clunky torque converter. A dash display indicates how many cylinders are working and when. Fuel mileage is improved up to eight percent with DOD, Chevy says: EPA for the V-8 is 18-mpg city/28 highway. Premium fuel is recommended to achieve the full 303 horses, but not required if you can get along with fewer.

Inside, the redesigned interior is well done, even on the base LS model. The LT is the next step up, and the only one offered with the 3.5 or 3.9 engines. The LTZ has only the 3.9. The SS, which Chevy figures will account for about 10 percent of Impala sales, has the all-aluminum 5.3 plus a stiffer suspension and P235/50R18 W-rated radials. The 3.9 has P225/55R17 tires, and the 3.5 has P225/60R16s. All rubber is Goodyear. The SS's suspension is the stiffest of the Impala quartet, but considerably less stiff than its V-8-powered cousin, the Pontiac Grand Prix GXP.

As before, six adults can fit in the Impala, but five would be happier, and four downright cheerful. A flip-down center console makes the front bench seat seem like a pair of buckets. The neatest interior update: Rear-seat bottom cushions tilt forward, minivan-like, and the seatbacks fold flat. That space, opening to the 18.6-cubic-foot trunk, makes for an enormous storage area--or a great dog run.