The implementation of energy efficiency measures (EEMs) is the primary means of improving industrial energy efficiency (IEE). Almost 69% of industrial electricity use emanates from motor systems. IEE has traditionally been explained with technology-diffusion models. According to these models, increased diffusion of more effective motors and drives onto the market leads to improved efficiency. Electric motor systems are represented by three levels: electric motor, core motor system, and total motor system. The first and second levels are related to standalone technology measures while the third has a more operational character. Based on a unique dataset of implemented energy-efficiency motor system measures from the 100 most electricity-intensive industrial companies in Sweden, the aim of this paper is to study whether technology diffusion is a valid model for understanding improved energy efficiency in electricity-intensive industries. Results show that 59% of the implemented EEMs from the dataset go beyond technology diffusion models, implying a need for revised models to understand how energy efficiency and technology diffusion occur in energy-intensive industry.