I doubt it would do any good. There is a low pressure region behind the car that causes the air to circulate. You can see the vortices behind the car if the is smoke, dust, light snow, etc.

a three foot extension that sticks out behind the car might work....but would certainly look like hell. I'd rather wash it every week or so myself.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

How about a big chrome vertical stack, just like a semi?

or two of them....

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I don't know that a chrome tip would help much, but I had a problem with soot collecting on the back of the Volvo diesel and clouding the back up light in the left rear light cluster as well (LOTS of soot!). My mechanic replaced the tail pipe with one that points out to the left of the car between the rear wheel and the rear bumper instead of pointing right out of the back of the car.

I haven't had problems since with the soot....although when the wind is blowing from the rear of the car to the front and I leave the door open when I start the car, the plume of smoke on start up exits the pipe, hits the open door and is directed into the cabin!!

Oh well, at least the back looks better...

__________________
Christopher
'06 Mercedes E350 station wagon (silver/black)
'85 Mercedes 300D (black pearl/palomino)
'85 Mercedes 300SD (smoke silver/burgundy)
'79 Cadillac Sedan DeVille

'05 Toyota Camry (because always running is nice)

'85 Mercedes 300D sold back to orig. owner 8-1-06
'84 Volvo 264GL Diesel, owned 2000-2013

Yes , it works as I do this to most of my old cars and have been adding slash cut exhaust tips for years and years ~ if I just _think_ of an idea , I'll say so ,
not foist it off onto you guys to experiment with

You're entirely correct about the swirling Vortex behind the car , I see it at every traffic light and stop sign at night , this is why I'm obsessed with eliminating the smoke...

-Nate

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better