The 4Runner SR5 and Trail 4x4 models have a two-speed, part-time four-wheel-drive system with neutral position, maximizing fuel efficiency when a 4x4 configuration isn't needed. The 4Runner Limited is equipped with a full-time, four-wheel-drive system with a locking center differential and a three-mode, center console-mounted switch.The A-TRAC traction control system is standard equipment on all 4x4 models. The system can distribute driving force to any one wheel in contact with the ground, making terrain irregularities and slippery patches virtually transparent to the driver. An electronic-locking rear differential is standard on the Trail grade. The Trail grade is designed to maximize off-road performance with superior approach and departure angles, high ground clearance, and an array of functional upgrades for the most demanding active outdoor enthusiast. The Trail grade offers an optional Kinetic Dynamic Suspension System (KDSS). KDSS significantly improves terrain-following ability by dynamically disconnecting stabilizer bars to allow for more axle travel, and better suspension articulation in slow, difficult terrain. Toyota's Crawl Control (CRAWL) feature is standard on the Trail grade. The system helps maintain an appropriate speed to keep the vehicle under control and minimizes the load on drivetrain and suspension components. With the transfer case shifted into low range, CRAWL regulates engine speed and output (along with braking force), to propel the vehicle forward or in reverse at one of the five driver-selectable low-speed settings. This allows the driver to maintain focus on steering over rough level ground or steep grades without having to also modulate the throttle or brake pedal. The Trail grade also features a Multi-Terrain Select system that dials in wheel-slip control to match the terrain. In loose terrain such as mud and sand, more-than-normal wheel slip is permitted, allowing wheel-spin to work in the vehicle's favor. On bumpy moguls, or solid rock, wheel slip is minimized and the system acts more like a limited slip differential. The Mogul setting is for any extremely uneven terrain, such as V-ditches, slopes, and ridges, uphill or down.