The Multiple Streams Framework is applied to investigate why material efficiency solutions are currently a limited part of the climate policy agenda. The case study under investigation is the UK agenda to reduce greenhouse gas emission from cars. Evidence from 14 semi-structured interviews, document analysis and academic studies is used to develop and substantiate the arguments made. In the UK, inefficient material use is only perceived as a problem insofar as it increases in-use vehicle emissions, which disadvantages some material efficiency solutions. The appeal of material efficiency solutions is further limited by a lack of real-world and modelling evidence, creating uncertainty around the anticipated costs and impacts of any policy intervention. Recent political developments are unlikely to make the UK government more receptive to the problem of greenhouse gases arising from inefficient material use in the future. This is further compounded by policy lock-in. Although a small community of policy entrepreneurs are promoting material efficiency solutions, they have disparate priorities, which impacts their effectiveness. The insights from this paper can inform future research and policy entrepreneurship to increase the likelihood of material efficiency solutions becoming a larger part of the climate policy agenda. The problem of climate change is too significant for any potential solutions to remain underexplored by policymakers in the UK and the rest of the world.