The real explanatory variable, as the previous chapter showed, is policy architecture: the combination of tax incentives, registration structures, and running-cost advantages that shape the total cost of ownership.
This paragraph should be integrated into the box titled "GDP doesn't explain it either.". The idea that the real explanation as to which countries have better results is found in the policy architecture should be the last idea in the "box" talking about GDP. Just make sure its not mentioned twice, since its already written tehre as well.