Environmentally conscious Susan has been told that a new electric car will only generate 6 ounces of greenhouse gases (GHG) per mile, but that a standard internal combustion car is double that at 12 ounces per mile.

However, the nature of electric cars is such that the new technology and electric batteries generate 30,000 lbs. of GHG to manufacture and another 10,000 lbs. to recycle. A standard car generates only 14,000 lbs. of GHG to manufacture, and recycling with established technology is only 1,000 lbs.

Susan is interested in taking a systems approach that considers the life-cycle impact of her decision. How many miles must she drive the electric car for it to be the preferable decision in terms of reducing greenhouse gases?