Currently, according to the assumptions of Industry 4.0 or even Industry 5.0 (I4.0/I5.0) customization of products in production is an important issue not only for researchers but also for the production managers. Supporting decision-making in the Mass Customisation (MC) production is particularly important due to the need to balance maintaining cost effectiveness, high quality of products and customer needs satisfaction. The main goal of this study is to analyse the possibilities of supporting decision-making in the context of the improvement of MC level in the automotive industry using correlation analysis and Analytic Hierarchy Process (AHP). The research was based on an analysis of scientific literature and empirical research in the industry. Firstly, this study indicates the impact the parameters within production planning on the improvement MC level in the automotive industry. Next, the results achieved highlighted the core criteria within production planning within MC, namely production volume in relation to the production volume target and electricity consumption per manufactured product. The findings of this study revealed the main future research directions in this area: (1) creating a methodology of the MC production improvement in the context of ensuring fulfilment of individual orders and (2) developing the approach to monitor the electricity consumption within MC production.