ECU trends at SAE Convergence

He (Steve Magner of Ford Motor Co) used the term "high degree of freedom" (HDOF) to describe the typical modern powerplant, and explained that the table-based method ("full factorial mapping") of calibrating ECUs has basically reached its limit. Where as it's desirable to complete the calibration of a new engine in about four months, a HDOF engine currently requires up to 15 months to fully define in the laboratory. In one example, developing just the timing maps for the EPA' s fuel economy test cycle involved 630 states of operation and three months of time on the dyno.

Via Autoblog