A simple model for driver and vehicle in longitudinal motion is developed and simulated. The focus is on describing and handling simulation of clutch lock and clutch release which changes the model structure, both during start and gear shifts, in Simulink. Special attention is given the problem of simulating start and stop of a vehicle with rolling resistance at zero speed. Only principles for simulating the system with variable structure is of interest and therefore the models are maintained at lowest possible complexity. The system is successfully simulated and the validation is performed using three scenarios: one with only clutch lock and clutch release, one with start and stop of vehicle, and one full European drive-cycle.