text: Engineers used a variety of high - tech materials, redesigned many key parts of the engine, new valve coordination, and a new exhaust system?
classes:  No, engineers emphasize the use of cheap, traditional materials to save costs.  Besides, engineers emphasize the use of cheap, traditional materials to save costs.  Yes, engineers emphasize the use of cheap, traditional materials to save costs.  Meanwhile, engineers emphasize the use of cheap, traditional materials to save costs.