Soot. Under heavy torque loads the diesel engine's fuel injection system will keep the injector open longer, which shoots more fuel into the cylinder. That means more power, but also a rich burn condition that doesn't burn as completely as just cruising.

The vast majority of trucks on the road are diesel. Pretty much any vehicle you see that is larger than the largest pickup truck is going to be a diesel - not a guarantee, but a safe bet. The diesel delivers great torque at low speeds, and delivers more power from the fuel it burns than a gas engine. As expensive as it is to operate a big truck, a gas engine would cost more - fuel price discrepancy notwithstanding.

Biodiesel soots just the same as petrodiesel. The operation of the truck is the same.


The exhaust literally is heavier - it's soot. It falls out of the air and then you don't have to breathe it - it gets washed away in the next rain. And that Doesn't happen with gas engines, their exhaust stays in the air so we can breathe it over and over.