Subcontractors are commonly involved in several quotation processes and new requests for quotation are continuously received from clients. To be able to respond with feasible design solutions at competitive price, new ways of working has to be adopted, especially when it comes to quotation preparation. High levels of accuracy of the preliminary design solutions and the cost estimations generated in the quotation process are a necessity. The purpose of this work is to investigate, explore, and develop a computerized method to support quotation preparation. The main objectives are to reveal concepts and principles to support application system development and evaluate the applicability of automated quotation preparation. The results are based on experiences from a case study at a sub-supplier to the car industry. In the case study, a design automation system for quotation preparation of seat heaters was developed. The system supports the pursuit of a valid design solution and the best solution in the individual case enabling the company to respond quickly with a competitive price when receiving a new request. In this paper, principles and concepts supporting system development are introduced and the system’s applicability as a means in quotation preparation explored.