What is the most environmentally friendly car to use?

Question

Consider someone that needs to use a car for some things. They can bike, walk, and use public transport as much as possible, but still use a car. It's trivial to find out what cars have the least emissions, but what type of car would it be if you consider the total lifetime environmental impact, and the second-order affects from the used market that occur because of one's choice? How would a total environmental impact metric be measured (combination of all CO2 emitted, rare metals mined, etc)? How would you find the details involved in the calculating the metric?The priority is understanding it for average use, not as much the case where the car sits most of the time with little emissions at ~500 miles (800 km) / year.From perusing HN over the years, my inclination was towards an old, low emissions hybrid like a Prius. I realized this was more of a gut feeling and wanted to understand it better based on hard numbers and what metrics are most environmentally concerning.Is it a used, high-mileage, low-emissions hybrid? Used BEV? New BEV?

kazinator · Accepted Answer

Let us begin with the observation that an entire star had to explode to produce the heavy elements like iron, needed for key structural parts of the automobile. If we can shake off that guilt, we can move on to the minor issues, like energy use for mining the ore, smelting and such.

mister_hn · Answer

Old Priuses might need a battery replacement, which affects the environment itself and your pocket (it might costs you $10k).

ReptileMan · Answer

Without giving details on how much and for what the car will be used it is impossible to answer.