In this work, an efficient implementation of a zero-dimensional model is described for the estimation of key engine parameters for combustion control in compression-ignition engines. The direct problems of the estimation of the angle of 50% of fuel mass fraction burnt (MFB50) and of the Indicated Mean Effective Pressure (IMEP) are addressed as well as the inverse problems of determining optimal start of injection (SOI) timing for target values of MFB50 and IMEF. The main focus is on the computational cost of the algorithms proposed, designed in order to keep the number of operations as low as possible without compromising the applicability of the methods to different engine configurations and operation points. Execution time of the order of few milliseconds is achieved for parameter prediction and of the order of one tenth of a second for the optimization problems, such that an implementation in engine ECU for model-based control purposes can be envisaged. (C) 2015 Elsevier Ltd. All rights reserved.