Modeling internal combustion engines is challenging due to the various coupled multi-physics phenomena. With the advent of modern supercomputing and advanced modeling techniques, studying and designing these engines through detailed simulations is becoming tractable. Since the combustion process is the primary controlling feature in these engines, a high fidelity combustion model is essential. This model must be efficient and valid across different combustion regimes, since modern engines might operate in hybrid modes. The Representative Interactive Flamelet (RIF) combustion model is a possible choice. This model has been developed to describe ignition, combustion, and pollutant formation in direct-injected diesel engines. However, it has recently been shown that the model has the correct asymptotic behavior for both diesel and Homogeneous Charge Compression Ignition (HCCI) regimes, and the model has been applied successfully for HCCI type combustion. In this study, the model is validated against two-dimensional direct numerical simulation data with multi-step finite rate chemistry to evaluate model performance in the diesel, the HCCI, and hybrid regimes. A wide range of temperature and mixture fraction stratification cases are simulated to evaluate the model performance across different modes. The model performs well for all cases considered, even when high levels of concurrent thermal and charge stratification are present. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.