The Birth of the Prius by Alex Taylor III:
Seems like a good job of providing a vision of what was needed without overly restrictive targets and goals (See: Targets Distorting the System).
While targets and goals can distract from improvement some guidance is useful. If the desire to is have incremental improvement one strategy may be reasonable but if the desire is to aim for huge improvement another strategy is likely required. In general target are far too specific and overused so as a general rule I am inclined to be biased against targets. However the proper use of "soft" targets (doubling or in the range of 10% for example) to define the scope of an effort make sense.
Investing in innovation is risky. If successful, the benefits can build a competitive advantage that is difficult for others to eliminate. However, others will try and if you fail to execute as well in the future those benefits can disappear quickly. Toyota shows few signs of letting others catch up though.