Why do diesels exhausts point downwards?

[yertis]

As the title obviously. Trucks and buses have exhausts exiting directly from the side or on some big trucks pointing so as to direct their vile fume directly into the firmament. Why do cars have them pointing at the road?

[Balmoral Green]

Mine doesnt.

[Wigeon Incognito]

I've always assumed its to stop all the soot accumulating on the nice shiny car - could be wrong!

[up-the-dubs]

I've always wondered this myself. There are very few diesels that don't point down. iirc there are a few VAG group cars that don't.

Why?

[sadako]

Cut the end off, just go fast enough so the dirt ends up on the tailgater

[Pat H]

yertis said:

Why do cars have them pointing at the road?

Cos they are ashamed of themselves?

[Balmoral Green]

Used to have a Fiat Ducato based motorhome with a side exhaust, used to put a sock over the pipe when I started it up on campsites to catch the smoke and soot. Considerate to my fellow campers

[fid]

Tis just to help keep the clouds of soot down low...BMW common-rail diesels, and a few others, have a straight exhaust because, apparently, they don't blow clouds of soot.

[mab1]

i think some of the sporty bmw diesels have straight exhausts now.

I think it is to stop the back of the car getting filty.

[DennisTheMenace]

saw a bm with a stright exhaust today , its arse was black with soot , so they have cleaned them up then .... can even see the exhaust on the 1.5 powerstation that is the scenic . perhaps they never fitted one because it would upset the power curve of the beast .

[TVR MAN]

Balmoral Green said:

Used to have a Fiat Ducato based motorhome with a side exhaust, used to put a sock over the pipe when I started it up on campsites to catch the smoke and soot. Considerate to my fellow campers

Did the sock ever go on fire?

[deltafox]

Just put your face in front of the open pipe Yertis as someone starts the bloody thing up....youll soon see why they point down...

[toast boy]

If you put a stainless performance exhaust on a diesel, would it sound any better, or would it still sound like a tractor? Just wondering, because I don't think I've ever seen it done.

[vee]

mab1 said:

i think some of the sporty bmw diesels have straight exhausts now. I think it is to stop the back of the car getting filty.

Yes but they charge you for a particulate filter in order to have straight exit pipes.

[Trooper2]

It helps with exhaust noise to point them down.

[LuS1fer]

As I found out this morning from a diesel Fiesta in front, it's to allow huge clouds of smoke to stay close to the road so it can be sucked into the fresh air vents of the car behind. Stinking horrid devices.

[WWESTY]

..........cos they'd look pretty silly pointing up...........??

[victormeldrew]

LuS1fer said:

As I found out this morning from a diesel Fiesta in front, it's to allow huge clouds of smoke to stay close to the road so it can be sucked into the fresh air vents of the car behind. Stinking horrid devices.

Can we arrange for the exhausts of Metros to point down as well then, the unburnt hydrocarbons these almost always belch out make my eyes water. Stinking horrid devices.

[dieseljohn]

I think it is a combination of noise and soot. Mostly soot. Modern diesels do sound a little better than they used to, so this along with filters may be the reason behind the move towards straight pipes.

[shadowninja]

the irony... got this ad on this thread: