Nissan have made big changes to the Altima's drivetrain, offering all-wheel drive for the first time and replacing both engines in the car's lineup. The new base engine is a 2.5L 4-cylinder, like the one it replaces. However, the new engine makes more horsepower (now up to 188) while also reducing noise, vibration and harshness over the one it replaces. Power is sent to either the front wheels or to all-four wheels via a continuously variable transmission (CVT.) The optional engine in years past was a V6, but Nissan have opted instead to replace it with a turbocharged 4-cylinder engine, offering better fuel economy while making similar power. Once again, a CVT is used to send power to the front wheels, though all-wheel drive is not offered with the turbocharged engine. The Nissan Altima is offered in several different trims: S, SR, SV, SL and Platinum make up the main trim levels. The base S version is still relatively well equipped, even if it doesn't come with all of the driver assistance technology available on some of the more expensive models. Standard features on the S include cruise control, automatic headlights, push-button start, a 7-inch color touchscreen display, a Siri Eyes Free mode, Bluetooth, 4 USB ports, speed sensitive volume controls, an intelligent forward collision warning system, a rearview camera, a hill start assist system and an automatic emergency braking system. The SR trim adds a dose of sportiness by including 19-inch wheels, a sport tuned suspension, paddle shifters and LED headlights. Buyers opting for the SV trim get Nissan's ProPILOT Assist system, which aids drivers by taking care of some of the more mundane tasks of driving for them. For instance, ProPILOT Assist can keep a specific distance from the vehicle ahead, even in stop and go situations without any input from the driver. It will also help steer the car, subtly keeping the car within its lane. While the system doesn't offer a fully autonomous mode, it is part of the way there and should significantly ease the stresses of a daily commute. Stepping up to the SL trim adds a navigation system, SiriusXM Satellite radio and a bigger Bose stereo featuring 9-speakers. In addition, the SL trim has leather lined seating surfaces and a power adjustable front passenger seat. The Platinum trim includes a memory function for the driver's seat and an around-view monitoring system which uses several cameras to give drivers an unparalleled view over what's going on around them. Safety features on all trims include lane departure warnings, forward collision mitigation, pedestrian detection prevention and a driver attention alert. All trims except the S also have a blind spot warning system, rear collision mitigation and parking sensors.