The relationship of engine revolutions to drive-wheel revolutions, expressed as a ratio. The transmission allows gear ratios to be changed, while gearing at the differential (called the "final drive ratio") is constant. Gearing is expressed as a ratio, such as 3:1 (three input revolutions for every one output revolution). The higher the first number, the lower the gearing. Low gearing (numerically high, such as 4:1) provides faster acceleration and reduced fuel economy; high gearing (numerically low, such as 1:1) provides slower acceleration and better fuel economy.