The paper examines the effect of heterogeneous consumer demand on the generation and diffusion of environmentally benign technology paradigms. The history of the shift from horse-based to car-based transport provides the basis for an empirically grounded multi-agent model of sequential technology competitions. Firms compete on price, product quality, and the environmental sustainability of their products, and improve their market position through product innovation. The trajectory of product innovation is shaped by the distribution of heterogeneous consumer preferences with regards to quality, price, and the environmental impact of consumption. The distribution of consumer preferences determines whether cleaner designs are developed within a technology paradigm, whether new, more environmentally benign paradigms are developed, and whether these new paradigms replace older, environmentally harmful technology paradigms.