Ever seen the Steven Spielberg film, Duel?
The film, its plot about an unseen trucker terrorizing a hapless motorist, no doubt conjures a few preconceptions about truckers and the smoke-spewing beasts they command.
Truckers aren't as scary these days, nor do their chariots pump huge smokey stacks into the air--in fact, nearly a third of modern trucks use the latest, low-emissions clean diesel engines.
That's around 2.5 million of the 8.6 million trucks registered in the United States, cleaning up the countrywide fleet significantly.
Since 2007, reports the Diesel Technology Forum, all heavy duty diesel trucks sold in the U.S. have had to meet stringent particulate matter standards.
Emissions of just 0.01 grams per brake-horsepower hour (g/HP-hr) mean tailpipe emissions have reduced considerably, and cleaner-burning engines mean nitrogen oxides (NOx) emissions are also much lower--data compiled by R.L. Polk shows it a full 99 percent since the pre-2007 days.
Fuel economy itself is also rising, with engine advancements and improved aerodynamics contributing to a 3-5 percent improvement since 2010.
There's potential for more, too. While a typical long-haul truck averages 5.5-6.5 mpg, Cummins and Peterbilt recently displayed a 9.9 mpg truck, using little more than half the fuel of the average truck.
So what about the two-thirds of trucks that aren't yet the latest, cleanest models?
It isn't all bad news: Because the fuel itself is getting cleaner, with lower levels of sulfur and the availability of retro-fit parts for existing diesels, it's still possible to reduce emissions from those models by as much as 90 percent.
And while natural gas trucks are now being considered for wider use to clean up emissions further, diesel is still the major fuel for cargo transport. Diesel Technology Forum's Allen Schaeffer cites figures that 82 percent of U.S. cargo is moved by diesel--so the fuel is hugely important, and cleaning it up even more so.
With clean diesel truck sales growing by as much as 4.5 percent per year, each product that reaches your door has used just a little less energy and polluted a little less to get there.
We can't guarantee the driver hasn't scared a few commuters on the way, though...