Physical modeling of heavy oil recovery processes is a critical step in evaluating their technical feasibility. Results from physical modeling studies, in conjunction with simulation and analytical modeling, are key to technically justifying field trials and pilots. Proper scaling of reservoir model dimensions, reservoir properties and energy boundary conditions, operating condition monitoring and control, and production data analysis are very important aspects of physical model design and operation for evaluating the performance of a heavy oil recovery process. This paper describes physical modeling and performance evaluation of the Solvent-Assisted SAGD (SA-SAGD) process applied to Athabasca oil sand reservoirs with focus on process optimization under low operating pressure condition. The paper presents the design features of the physical model used for testing that ensures reliability and reproducibility of the experimental results. The results of laboratory testing are shown with emphasis on demonstrating the reliability and reproducibility of the test results.