I'll need to look for it.
But the basic idea is that it takes a lot of energy to make a new car.
The pollution the old car makes is better than making a new one, even if it is more economic.
I don't remember if this for the cost of disposing or recylcing the old car.
But it doesn't take into consideration the concept of "pollution localization".
Where pollution is localized in cities and countries, but rather looks at pollution as a total from the planets point of view.
I'm not sure if that is true or not.
But in environmental economics, it is best to reuse than to recycle.
So you are essential "reusing" the old car.
The hybrid "recycles" its energy.