The last models of SS Impalas produced in 2009 offer different horsepower outputs than the Impalas made during the first years of production. The 2009 SS Impala provides 303 horsepower at 5,600 revolutions per minute. The 2004 SS Impala offers 240 horsepower at 5,200 revolutions per minute.
The final 2009 SS Impala model produces more torque output than the 2004 SS Impala model. The 2009 SS Impala produces 323 pound-feet of torque at 4,000 revolutions per minute, while the 2004 SS Impala can produce 280 pound-feet of torque at 3,600 revolutions per minute.
In terms of fuel economy, the 2009 SS Impala offers 16 miles per gallon in city driving and 24 mpg on the highway. The very first SS Impala made is actually more efficient than the final Impala SS model. It offered 18 mpg in the city and 28 mpg on the highway.