Modern powertrains are highly complex systems whose development requires careful tuning of hundreds of parameters, called calibrations. This paper presents a methodology for automatic generation of calibrations for a powertrain-abstraction software module within the powertrain software of hybrid electric vehicles. The module encodes the powertrain's torque-speed equations as calibrations. The methodology commences with modeling the powertrain in MapleSim, a multi-domain modeling and simulation tool. Then, the underlying mathematical representation of the modeled powertrain is generated from the MapleSim model using Maple, MapleSim's symbolic engine. Maple is further used to manipulate the powertrain equations to produce the representation required for calibrations extraction. The methodology has been applied successfully in a research project with a large OEM (Original Equipment Manufacturer), leading to significant improvements in the calibrations generation process. It has since been integrated into the OEM's model-based development process.