The objective of the research reported in this paper was to develop and utilize a high fidelity and computationally efficient model for an advanced 9-speed automatic transmission that features an innovative combination of positive clutches (interlocking dog clutches) and conventional wet clutches. The interlocking dog clutches utilization in automatic transmissions is a challenging task due to the need for seamless engagement of the clutches (avoiding clash) and the behavior of slip-less power transmission (shifts). This publication starts with in depth review of the literature related to transmissions equipped with interlocking dog clutches. Appropriate simulation models for the torque converter, the lockup clutch, transmission gearing system, interlocking dog clutches, wet clutches, hydraulic control valves and circuits were developed and integrated with a 1-D vehicle road load model. The models were developed in AMEsim® software and the related mathematical models were derived for further investigations. The integrated powertrain system model was calibrated in order to estimate the unknown model parameters. The calibration process was conducted automatically and the estimations results increased the system's fidelity. The comprehensive powertrain model was used to compare simulation results with the measurement during various shift events including downshifting upon brake command. The results showed good agreement with the measurement data. This permitted investigating the dog clutch engagement dynamics under different engine torque generation profiles during hard braking.