If you're looking for power and performance in the 2008 Chevrolet Impala, you'll need to go for the SS version--the others are lackluster at best.
The base 3.5-liter engine powers the 2008 Chevrolet Impala with enough authority for most buyers' needs, while the 233-horsepower 3.9-liter V-6 offers noticeably more torque off the line, which may be more useful with a full load. Both engines are smooth when cruising but coarse under acceleration. Car and Driver says "the idea of the base 211-hp, 3.5-liter V-6 would drop our eyelids, [but] the 3.9-liter V-6 is not a bad choice in this car...it feels strong, even at higher rpm and speed, and never sounds labored," adding that its "233 horsepower is enough to giddyap to 60 mph in 7.4 seconds." Edmunds proclaims it’s “plenty powerful.” ConsumerGuide notes that "3.5 and 3.9-liter V6s provide similar acceleration in around-town driving, but the 3.9 has better passing response in the 35-55-mph range." All Impala engines are capable of running on E85 ethanol fuel.
The SS's 5.3-liter V-8 makes 303 hp and transforms the Impala to a more sophisticated performance sedan--capable of reaching 60 mph in well under 6 seconds--with an ever-torquey character and responsiveness at any speed. The only downside is that torque steer (a pull to the side) can be an issue coming fast out of tight corners. In comparison to the larger V-6, the V-8 propelled the Impala SS from 0-60 in just 6.5 seconds, and ran the quarter-mile in 14.5 seconds, offering what Edmunds describes as "serious thrust." ConsumerGuide notes the "SS's V8 furnishes ample power at any speed."
"A four-speed automatic is standard on all Impalas," says Car and Driver, and Cars.com tells us it "works with all three engines." Edmunds notes, “All models employ front-wheel drive and a responsive four-speed automatic transmission.” Many competitors offer six-speed automatics in the class.
This Impala Chevrolet's 3.9-liter V-6 uses Chevrolet 2008 Active Fuel Management technology to shut down one bank of cylinders when coasting or cruising at freeway speeds, which "increases gas mileage by as much as 8 percent," according to Cars.com; the same technology shows up on the V-8 as well. ConsumerGuide tests find that "an LT 3.5 averaged 24.2 mpg on conventional gasoline in mostly highway driving," which drops significantly using E85. They also report that "an SS averaged 20.3 mpg in mostly highway driving." Edmunds cautions that though the SS “may be tempting to power-hungry buyers, be forewarned that sampling its formidable reserves quickly brings fuel mileage down to the high teens, with official 2008 EPA ratings of 16 city and 24 highway.”
The Impala's ride definitely skews toward comfort, but the tighter tuning of the SS model's FE3 suspension--and the FE1 suspension that's included with the 3.9-liter engine--brings crisp handling without much of a ride sacrifice. ConsumerGuide reports the Impala is "stable with good steering feel," especially the SS model, adding "stopping control is good." Edmunds feels the "cushy suspension hurts handling dynamics.” According to Car and Driver, "the Impala soaks up bumps well" when traveling in a straight line, but "once the road starts to wind, the Impala dips, leans, and squats as though the road were one big yoga mat." Kelley Blue Book notes "the top-level Impala SS has a suspension firm enough to encourage enthusiastic driving on curvier public roads." It’s a “forgettable driving experience” in all but the SS versions, Car and Driver concludes.