The growing importance of environmental awareness in consumer behavior makes understanding attitudes towards green products crucial. This research aims to provide a practical model to deal with uncertainties, ambiguities, and insufficient data in quantifying and analyzing consumer attitudes in the context of sustainable consumption. To achieve this, an innovative combined approach of the SERVQUAL model based on Dynamic Grey Relational Analysis (DGRA) was developed to transform subjective feedback into measurable grey numbers for evaluating the gap between consumers' expectations and perceptions. Considering population aging challenges, the attitudes of elderly consumers aged 60 to 75 were considered for the practical analysis of the proposed framework. Key findings revealed substantial negative gaps between expectations and perceptions across most quality dimensions, suggesting green product attributes often do not meet anticipated standards, especially regarding environmental features. The results highlight an urgent need for brands to elevate product quality and enhance transparency in order to align with the evolving values of green consumption. The study emphasizes the need for transparent and accurate marketing to address gaps in consumer perceptions, build trust, and foster sustainable consumption practices, contributing to global sustainable development efforts.