> ex·ter·nal·i·ty: a side effect or consequence of an industrial or commercial activity that affects other parties without this being reflected in the cost of the goods or services involved
The buyer is an "other part[y]" from the seller's (edit: or better yet, developer, who might just be contracted by the ultimate seller...) perspective, and performance is basically impossible to quantify, therefore price.
Moreover, even if you want to limit externalities to being completely third-party... sure: Pollution. More electrical generation capacity needed.
A less efficient car engine means that the magnitude of the externality (in this case, the externalized cost, you can have externalized benefits as well) is larger.
> ex·ter·nal·i·ty: a side effect or consequence of an industrial or commercial activity that affects other parties without this being reflected in the cost of the goods or services involved
The buyer is an "other part[y]" from the seller's (edit: or better yet, developer, who might just be contracted by the ultimate seller...) perspective, and performance is basically impossible to quantify, therefore price.
Moreover, even if you want to limit externalities to being completely third-party... sure: Pollution. More electrical generation capacity needed.