In this article, a novel portfolio planning approach as a means to limit CO2 fleet emissions in the automotive industry is presented. This research is motivated by several factors challenging product portfolio planning in times of structural changes. Besides ever stricter CO2 legislation, dynamics and uncertainties related to the transformation towards electric mobility need to be considered when deciding on the future range of vehicles to be offered on the market. These portfolio decisions are of particular importance due to long life cycles, long development times and high product-specific investments of vehicle projects. This approach supports the definition of vehicle projects and cycle plans on an aggregation level in line with industry-specific planning requirements and allows for the consideration of temporal dynamics and uncertainties to handle structural changes. To this end, illustrative cycle plans are generated and evaluated based on financial and environmental criteria considering different scenarios of market development.