Range's V4 PLUS device, intended for older 4 speed vehicles, is a less aggressive calibration than our V4 MAX device. Range's V4 PLUS optimizes your performance by better identifying your driving situations helping you get more miles out of a gallon of gas.. Active Fuel Management (AFM), available on most GM trucks and SUVs, helps lower fuel costs by enabling V8 engines to behave like four-cylinder engines when cruising with light loads, while seamlessly unleashing their full muscle whenever needed. However, our testing has shown that factory installed AFM only drops to 4 cylinders 35% of the time even though the average driver requires V8 performance just 10% of the time. Through a sophisticated load-based algorithm, Range's V4 PLUS device allows you to drive in V4 mode 60-70% of the time - saving an average driver 35-40 gallons per year, or about $150. The Range product plugs directly in to your vehicle's OBDII port, but does not reprogram the factory ECU. Fast and easy setup. Simply plug in Range into your onboard OBD-II port and it instantly begins working with your Active Fuel Management to optimize your fuel economy.