The second example: reducing fuel consumption by a better aerodynamic design.
This is an example of the rebound effect in the automotive industry.
On first sight this is a win-win situation since the result is savings in eco-costs (at a high EVR) as well as savings in costs. The rebound effect, however, reduces the positive result in terms of sustainability considerably. See Fig. 4.3c.
Since the consumer preference is to spend a fixed part of the income on (driving) cars, the money saved on fuel is spend again on fuel in a country with no speed limit, like Germany. It results in driving faster, instead of savings on diesel consumption. In The Netherlands, a country with speed limits, the situation is slightly better: it results in driving more. Although “diving more” has a lower EVR than “driving faster” (the EVR of the diesel is higher than the EVR for the car+diesel), the end-result is that there are hardly any savings in eco-costs.
Concluding: sustainable products must have lower eco-costs, but at the same time higher value (market price), to avoid the rebound effect. See Fig. 4.3e.
More examples on this issue are given at the page product innovation: eco-efficient value creation.
Literature: see webpage references 2.0, 2.5 and 2.8.