Tailpipes under bumper

I was having a Starbucks and looking at cars in the lot, and I noticed that modern cars all seem to end the tailpipe now under the bumper. Not like in the old days (1960s, 1970s) where a rusty tailpipe would stick out an inch or two beyond the body.

Doesn’t it seem like the carbon monoxide would rise up into the cab (and I realize they seal these things now somewhat)? Doesn’t the heat stay within the wheel wells, or near the gas tank?

Cosmetically it’s better (I guess) but isn’t it simply disguising the deadly carbon monoxide?

The amount of CO coming out the tailpipe on modern cars is so small these days you can almost breath the exhaust. I said ALMOST… don’t try this at home. Cars are sealed much better and the amount of CO is so small it just doesn’t collect, it diffuses into the atmosphere. Plus, manufacturers don’t want that sharp, hot pipe to injure passers-by.

And as long as you’re moving, it’s swept out the back.

Even with no CO car (gas) exhaust would still be lethal due to almost no oxygen and lots of CO2.
Might last a little longer with a diesel since there’s some O2 left, but then there’s the soot…

Tailpipes are past the lip of the bumper, so the gasses can go straight back.
Extending the pipe past the bumper would affect the (2.5mph?) collision design.

Yup. In fact in some polluted areas the air coming out of the exhaust pipe is cleaner than the air that went into the engine.

If you look close at a lot of those bumper-exit exhaust pipes, the tips you see are not actually connected to the exhaust pipe, which is usually a smaller diameter pipe in the middle of the fake tips. This has the effect of insulating the bumper from the heat of the exhaust.

As with many other things that used to be purely utilitarian, exhaust pipes are now a fashion statement. They gotta look pretty, and a rusty old tip dangling down from below the back bumper doesn’t!

Actually the annoying trend these days is the exhaust that exits in the exact center of the bumper. This makes it very difficult to put a hitch back there. True, most of the cars that have the center-exit exhaust shouldn’t be hauling trailers, but they’re nice to have anyway to hook a bike carrier to.

I remember when the pipes went through the bumper and rotted the bumper out along with the pipe. I’m thinking 56 Ford for one. Not a good bumper to be found.

There is no gurantee that a tail pipe that did extend beyound the bumper would not pass exhaust under the car either. During traffic, you will get enough CO regardless. While driving, there is plenty of air passing under the car to move the exhaust to the rear and modern cars are all tested for exhaust infiltration…they know what they are doing in this respect at least.

I think part of the reason they don’t extend out now is that in older cars with no electronic engine management, a lot of soot was produced, especially under hard acceleration. This would get all over the bumper and back of the car if the pipes didn’t stick out a bit. I have personally seen this on older cars where the tailpipe was too short or had gotten pushed forward. With modern computer controls, there is very little soot (except on diesels) to mess things up, so the tailpipes can be a bit shorter.

I’m certain that there’s a D.O.T. regulation involved, but from a purely stylistic standpoint sticking the tailpipe straight out under the bumper (usually with a chrome or polished "tip) makes the car look sporty.

My 70’s Ford truck tailpipe exits towards the side, under the body panel, rather than the rear, under the bumper. I presume they did vented it out that direction b/c if you need to put a bail of hay in the back with the engine running, you can lift the tailgate without getting a snootful of exhaust gas.

Soot’s coming back - the direct injection engines put out a lot more soot that regular EFI. Changes will be needed as the US and EU put tighter standards on particulates.

I’ve read that. I had a feeling it sounded too good to be true. I’ve had my doubts about direct injection since I first read about it.