Detailed item info Model OverviewThe Impala. Chevy's top-seller for the last few years. is usually classed as a mid-size sedan. but it is one of the bigger mid-sizes around. As such. it is no surprise that the Impala boasts roomy seating and almost 19 cubic feet of trunk space. The 2008 Impala comes in four trim levels: LS. LT. LTZ. and SS. The LS and LT have a 3. 5L flex-fuel-capable V6. the LTZ comes with a larger 3. 9L V6 (with Active Fuel Management). and the SS has a 303-horsepower 5. 3L V8. The V6 engines have variable valve timing. while the V8 is mated to a heavy-duty Hydra-Matic four-speed automatic transmission plus performance-tuned four-wheel independent suspension. Beyond that. most of the differences between trims are in small tweaks. such as fog lights. aluminum wheels (both standard with the 3. 9L and 5. 3L engines) or heated mirrors (standard on the LTZ). As with most mid-size sedans. air bags. power windows. power locks. and air conditioning are standard across the line. In addition. Chevy includes one year of OnStar's Safe and Sound plan. ABS. StabiliTrak. and a tire pressure monitor system round out the standard safety features.