The 2015 Impala is powered by one of two engines, each mated to a 6-speed automatic transmission. Engine choices include a 2.5L 4-cylinder making 196 horsepower and a 3.6L V6 making 305 horsepower. The 2.5 features all-new stop/start technology, which shuts down the engine in certain driving conditions to reduce fuel consumption. Chevrolet claims that the V6 is the most powerful naturally aspirated V6 in its class. The Impala comes in a number of different trims including LS, 1LT, 2LT, 1LTZ and 2LTZ. LS trims are the most basic and feature cloth seats, a 6-speaker 100-watt sound system with a 4.2 inch color display, an 8-way power adjustable driver's seat, steering wheel-mounted audio and cruise controls, keyless entry, automatic headlights, a noise cancellation system, 18-inch wheels and a 6-month subscription to GM's OnStar service. 1LT versions get dual-zone climate control, heated mirrors, a leather-wrapped steering wheel and shift knob, nicer 18-inch alloy wheels and a better stereo, which features Chevrolet's MyLink System, as well as an 8-inch screen. 2LT versions are nearly identical but also include the 3.6L V6. 1LTZ impalas feature a bevy of luxury features. As in the LT versions, 1LTZ and 2LTZ are the same, save for engine choice. Both trim levels include features such as a remote starter, keyless access and start, a heated driver and front passenger seats, ambient interior lighting, a rearview camera, 19-inch wheels, HID headlamps, chrome door handles and LED running lamps. The LTZ models also come standard with a host of extra safety features, including a lane departure warning system, cross traffic alert, blind zone alert and rear park assist. The additional safety features of the LTZ are also available on LT trimmed Impalas. All Impalas though, feature anti-lock brakes, traction control, OnStar with automatic crash response, stability control and a total of ten airbags.