Never heard of this before, I looked it up, but I still don't get it -- you're not getting more power, you're not getting better fuel efficiency, you're not getting a smoother ride, what's the point - you're literally burning money for no reason?
Correct. And destroying your engine in the process. Beyond washing down the cylinder walls (cylinder/ring wear) and diluting the engine oil in the process (worse lubrication for the bearings), EGTs tend to go absolutely nuts during the process (you're on the oxygen limited side of mixture, not the fuel limited side a diesel is intended to operate in), which means you stand a good chance of doing damage to the hot side of the turbocharger (high EGTs tend to start melting the corner tips of the turbine blades first, which is an easy check for a used diesel - if the blade corners aren't right, the engine has probably been abused), and it's hard on the rest of the engine too.
It's quite literally as stupid as it sounds.
There are cases where you do want to run a diesel like that - some of the custom tractor pulling engines will smoke an awful lot while they're spooling up and pulling, but that's an engine that's making insane horsepower for a short period of time, and they don't have a particularly long service life (like any competition engine). I believe they run on the rich side to use the excess fuel to keep combustion temperatures down (a stoichiometric mixture is usually far, far too hot). But on a road engine, it's just pointless engine abuse for style points (among the few people who actually think it's cool).
I've only ever seen it once when I was in an EV Uber (it was a Model S) behind a pickup truck in Baltimore and the pickup kept blasting us with massive amounts of black soot (presumably because we were in an EV).
There's a political element of "Truck Driving Republican" vs. "EV Driving Liberal" that powers some of this. I think Elon has been at last partially trying to reduce this polarization with how he behaves online to widen Tesla's appeal (though maybe I'm attributing too much intentionality here).
On the west coast I was tailed super aggressively by a pickup in my model 3 on 280 which was a little scary (blinding me with headlights, switching lanes to stay 1 inch behind me). I watched cameras after to see if I cut him off or something, but I didn't. It has made me more wary of pick up trucks in general though.
That sucks. I wish it were an automatic open-and-shut case to prosecute dangerous driving / vehicular assault like this when a court is provided with dashcam evidence.
