The present research constitutes an engineering approach to the performance level prediction of starting a vehicle without use of a throttle. The study is based on a dynamic clutch engagement model. A computer simulation of engagement dynamics is used in order to study the lock-up mechanism and to develop proper prediction procedures. In addition, the engagement model is used to develop guidelines and recommendations in order to optimize the engagement system including clutch components, clutch controls, and engine controls.The mathematical model presented in this paper incorporates important, new features in comparison to similar models from previous publications. Consisting of two inertias, it includes not only elastic properties of the clutch damper but also varying engine torque and clamping (pressure) force. Functions of engine torque and plate load simulate the actual control process, including human factors.The mathematical model is used to determine sliding velocity, torque transmitted through the clutch, and the rate at which energy is dissipated during engagement. For various loading conditions, it calculates lock-up parameters such as slip time, damper twist angle, and total energy dissipated during a single clutch engagement. Also, it calculates transient torsionals including clutch torque overshoot.Numerical examples and detailed results of the clutch engagement study are presented and discussed. These results are used to identify key design problems such as the influence of engagement speed on vehicle performance and comfort, clutch endurance problem, etc. Some practical recommendations to improve engagement quality are made in the form of design specifications for cushion elements, clutch linkages, and engine controls.