APQP = concurrent engineering
IEEE Spectrum, July 1991 "special report on concurrent engineering (CE)"
John Deere & co used CE to cut 30 % off the cost of developing new construction equipment and 60 % off development time
Hewlett-packard decided to improve the quality of its products by 1000 percent in 5 years -- and succeeded! For example, on one product the devgelopment team for an oscilloscope developed the product from idea to finished product in 1/3 the time it took to develop similar products.
AT & T adopted CE and reduced the time it took to develop a new switching system by 50 %.
Institute for defense analysis (Wenner et al 1988) benefits of Ce included:
40 -60 percent reduction in developpment time
30-40 percent reduction in development costs
50 percent reduction in engineering changes
75 percent reduction in rework and scrap
There are other metrics similar to this in "Concurrent engineering effectiveness" by Mitchell Fleischer and Jeffery Liker. I highly recommend it!