Trucking accounts for one-fourth of the fuel used on U.S. roads

The Energy Department's Vehicle Technologies Office's "fact of the week" pulls data on 2 key categories of medium- and heavy-duty trucks to illustrate what prolific fuel users they are.

The big picture: As the chart above shows, in 2017 they consumed over one-fourth of the fuel used on U.S. roads despite being just 4.5% of the vehicles. "Combination" trucks alone — that is, tractor trailers — accounted for 17% of that consumption.

Why it matters: It's hardly just the U.S. where heavy trucking is a massive source of fuel consumption.

• Globally, trucking — as well as petrochemicals, shipping and aviation — explains why multiple projections of global oil demand see growth (or at least no decline) through 2040 or later.

What they're saying: The International Energy Agency's central long-term scenario shows oil demand is several million barrels per day higher in 2040, even though use in passenger cars peaks in the mid-2020s.

• All of that growth is expected to come from developing economies.

Go deeper: Self-driving cars could be more fuel-efficient than human drivers