2011 BMW 335d sedan
And it could at lat be something to do with used tires. Except for sandals, playground equipment, and the like, there aren't many products that use them. In the past tires were hauled miles away from cities and burned, but it appears that practice is mostly history. Instead the tires are merely sitting—and taking a very long time to break down because compounds have been getting increasingly good in recent years.
Now, a Basque researcher is using a process called pyrolisis—heating to a very high temperature without oxygen a process that will in just 30 minutes, decompose a tire into liquids, gases, raw materials, and soot. Both the liquids and the gases could be used as an alternative fuel, helping to displace fossil fuels. The liquids in particular are close to petroleum in makeup and could be used either in diesel fuel, or as heating oil, and overall, there's more energy in the products than needed to bring the tires up to temp.
In addition to the petroleum substitutes from the rubber, the steel from the tires' structure could then be easily turned around and recycled, separate from the tire compounds, and the remaining soot would be used for new tires or inks, according to the researcher.