As a pickup truck owner and user, the behavior discussed here embarrasses me no end. Now, the following most definitely is NOT rolling coal, per se, but there is a point those of you who aren't overly familiar with pickups ought consider, however.
Since approximately 2007, US diesel engines in passenger vehicles need be equipped with diesel particulate filters (DPFs). These appear late in the exhaust system, and are moderately analogous to the catalytic convertors with which gasoline engines have been adorned for quite some time.
On regular intervals, these DPFs receive a "burn boost" to oxidize the accumulated soot trapped in the filter. At such time, a properly functioning vehicle will emit a really surprising amount of smoke. Murphy's Law decrees this usually will occur at a red light when three Priuses are arrayed behind same pickup. Now, usually, this smoke will be white rather than black, but not always.
So....if you see a late model diesel pickup belching what appears to be an inordinate amount of smoke, and especially if the driver is not noticeably revving the engine, trying to burn rubber, or so on, there is a good likelihood that he (never seems to be a she...) is, in that sense, innocent, and that the engine and exhaust system is performing as mandated.
Now...I wish my '08 F-350 would so perform. Unfortunately, its ferschliggina DPF never has performed correctly, and I fear I'm in for a ridiculously expensive off-vehicle cleaning of that filter. But that is seriously OT.
