A number of turbocharging systems have been proposed for improving the drivability of diesel engines for heavy duty trucks. The systems studied here included resonant intake, wastegate, and variable geometry turbocharging. By imposing a fixed power, torque rise, and engine speed range, it was possible to evaluate the fuel economy impact of each approach. First Law and Second Law balances are included to illustrate the differences in the systems. It was found that variable geometry turbocharging provided the best fuel economy.