An engine produces power, but the transmission decides how that power reaches the wheels. By changing gear ratios, it lets a car pull away gently, accelerate smoothly, and cruise efficiently at highway speed. Modern transmissions are among the most complex systems in any vehicle, packed with hydraulic circuits, clutches, sensors, and electronic controls, and they’re also among the most neglected. Types You Are Likely to Drive Most cars today use one of three designs. A conven