A 1961 Impala was the first production SS vehicle, so it's fitting that the Impala SS once again sports a V-8. The 5.3-liter LS4 engine produces 303 hp and 323 lb-ft of torque and features Displacement on Demand for slightly improved fuel economy. The '06 Impala also has been redesigned, with new front and rear styling. Now all the Impala SS needs is rear-wheel drive and a manual transmission.