Accurate powerplant inertia information is important for noise, vibration, and harshness (NVH) simulation and analysis of vehicle dynamics, both for engine mount systems in isolation and as part of vehicle system models. Because of the amount of effort involved in experimentally testing for the inertia properties of an automotive powerplant, typical practice is to test a single build variation of that powerplant. This inertia property information is then used to approximate the powerplant inertia properties of the other build conditions.This paper evaluates the effect of powerplant build options on powerplant inertia properties. An analytical approach is used, where powerplants are assembled analytically from a database of component inertia information, and the powerplant inertia properties determined. Powerplant inertia property results for a set of four cylinder, in-line powerplants, with different build options, are presented. Additional data are presented demonstrating the effect on the powerplant inertia property results of representing some components as point masses instead of as distributed masses.From the results it can be concluded that powerplant build options significantly change powerplant inertia properties. Further, the results show that it is the spatial distribution of components as point masses that has the most significant effect on powerplant inertias.