Lower carbon foot print makes sense.
Big trucks are legally allowed to emit as much pollution as several dozen of today's cars. But many big trucks actually emit as much pollution as 150 cars.

impact that big truck pollution on the air we breathe.
Big trucks and buses are one of the biggest sources of pollution especially in urban areas. Diesel soot is a toxic air pollutant linked to human cancer. A new annual report by state and local clean air regulators concludes that more than 125,000 Americans will get cancer from diesel fumes. Other studies have linked diesel exhaust to the development of asthma. In many cities, diesel exhaust is the biggest source of fine particulate soot. For example, in New York City, diesels (mainly trucks and buses) constitute more than 50% of the particle soot. Diesel engines (including construction equipment) also emit about 30% of all smog-forming nitrogen oxides (NOx).

What else is wrong with fine particle diesel soot?
In addition to causing cancer, health studies have shown that fine particle soot can shorten our lives in other ways in fact up to 50,000 people die prematurely each year because of it.