Most vehicle manufacturers (VMs) and suppliers are achieving standarts of manufacturing cost, quality and delivery unthinkable 15 years ago. However, there is still room for significant improvement in the area of design - it is here that ultimate cost, quality and delivery are configured. With some 70 % of cost coming from supplied parts the need for the effective alignment of the design process between VMs and suppliers is obvious; less obvious is what such a design process should look like and how it can be achieved. This paper describes supplier answers to these questions, proposes an initial model and outlines the COGENT initiative - a tool for successful implementation. The increasingly competitive nature of the automotive industry has facilitated a move from childlike, contractual relationships with suppliers, to more mature 'partnership' type relationships. The focus is shifting from suppliers as manufacturers to suppliers as 'co'-designers and developers, aligning themselves with the future direction and day to day working of vehicle manufacturers. This change is not easy for either partner, because not only does it imply a change in processes but also a change in attitudes, many of which have been deeply embedded through past experience. This paper has presented a supplier viewpoint on the critical factors for achieving successful co-development relationships, these are communication, early involvement, goal setting, project management, attitude and culture. A model has been proposed to describe the essential elements of codevelopment implementation based on these supplier suggestions, and includes the three key elements of alignment, review and communication. The COGENT initiative has been outlined as practical tool already being applied within one major VM and its UK/European supply base. 40 suppliers have joined the COGENT process, 15 have completed the workshop phase and early results suggest clear improvements in design and development performance. The investment from both parameters from both partners is therefore being directly returned in improvements in the quality, cost and delivery of components.