The automotive industry faces major challenges to meet targets for emissions, efficiency, performance and cost; light weighting of parts using composites enables all of these to be addressed, except for cost. A key driver of cost of composites is the limited ability & capacity in the joining technology available. In project Light-Join, JLR, Nissan and their Tier 1 suppliers aim to develop a number of solutions that will enable cost effective integration of high performance composite components into volume car production. Light-Join aims to enable replacement of specific metal vehicle components with composites, specifically focussed on developing rapid joining solutions, raising the manufacturing maturity to produce a small scale demonstrator component (MRL5) and assessing the potential for scale-up to MRL9A. This project will develop a solution leading to 30% weight reduction for all-aluminium construction (for JLR) and 60% compared to an all steel construction (for Nissan). Critically this approach will have industry wide applicability, allowing a lower risk introduction of lightweight composite components to the mass market.