The 2005 Chevrolet Impala is available as a 4-door, 5-seat sedan. Starting at $22,350, the 2005 Chevrolet Impala Base is powered by a 3.4L, 6-cylinder engine mated to an automatic transmission that returns an EPA estimated 21-mpg in the city and 32-mpg on the highway. The top of the line 2005 Chevrolet Impala Police, priced at $22,350, is powered by a 3.8L, 6-cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 30-mpg on the highway.