2002 Acura NSX: 
Unit Body Aluminum Intensive Design

Disadvantages to this approach:

• Formability of aluminum is poor in conventional stamping methods (high scrap rate expectancy).
• Recycling problems associated with 5xxx and 6xxx series segregation, causing a wider variation in scrap revenues mixing alloys compared to steel grades.
• There is a cost penalty associated with using aluminum compared to steel of comparable strength and part performance characteristics.
• Insurance premium increase along with costly repairability in the field (see repairability section).
• Questionable dynamic performance increase in vehicle handling and fuel economy by this intensive use of aluminum based on case studies of comparable steel intensive vehicles (see High Performance section).
• In most cases, little or no increase in fuel economy results from intensive use of aluminum (see High Performance section).
• Currently, there are larger design lead times for tooling development with aluminum than for steel parts, including higher tooling development costs.  This is mainly due to the knowledge and experience base available for steel design and utilization.  Also, the difference in springback characteristics and less total elongation for aluminum make designing for manufacturability more difficult. 

Body-in-white and closure breakdown pictorial of the 2002 NSX.

2002 Audi A8: 
Space Frame Aluminum Intensive

Disadvantages to this approach:

• An increased level of skilled labor is required for space frame construction, since the joining methods are more complicated that the conventional stamping method, based on data for the 2002 model year Audi A8.  Most space frame vehicles on the market use fusion welding to join the extrusions to stampings or castings.  Fusion welding requires specialized operators to ensure good welds are made.  The new 2004 Audi A8 is said to have fixed some of these issues with use of laser welding and more automated processes. 
• Due to part variability, the extrusions must be manually positioned in the assembly fixtures for the A8 through the 2002 model year.  The newest generation A8 is said to have resolved some of these issues by use of hydroforming for improving dimensional tolerance, but this added procedure may prove cost prohibitive for Audi since it is a separate added process.  
• Aluminum extrusion use requires secondary operations such as cutting, bending, and hydroforming, which can drive up assembly costs considerably, since these processes are separate.  Steel also requires secondary operations but are performed in-line and in-sequence during the stamping operations.

Body-in-white and closure breakdown pictorial of the 2002 Audi A8.

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