Dual Exhaust

Hi There,
I live in pennsylvania and it’s cold here. I was behind a car with two exhaust pipes and there was a lot of vapor comming out of one side and very little or none from the other side.
I know how dual exhausts are supposed to work and was wondering if this was normal or could the two tail pipes just be a selling point?
I know some are probably fake but do they go into the muffler as one pipe and come out as two or what?

It depends on the age of the car. Many newer cars have only cosmetic dual exhaust. Many more have only a single exhaust until it splits to go to two exposed tips. Not many short of the highest performance models actually have two exhaust paths from the engine (with dual catalytic converters, etc.) Older cars can have any of the above, but a dual exhaust probably is really dual, and might be isolated to each side or cross-connected with a header tube. Left bank/left exhaust and its mirror are cheaper and easier to tuck under bodywork, but a correctly sized and positioned crossover tube can increase horsepower, sometimes by startling amounts.

So you might have been seeing one real and one fake tip, or two real tips with a problem on one cylinder bank. Even with a crossover tube, oil smoke etc. will tend to stay on one side.

My car has dual tips, but at idle, exhaust only comes out of one side. Under certain throttle/load conditions, a flapper valve opens and a second chamber of the muffler comes into play and the both tips are ‘working’.

On some old cars, we’re talking '60s here, the exhaust on some V8 engines would be diverted from one exhaust manifold, through a passage in the intake manifold, and out the other manifold. This helped the engine and carburetor warm up faster. So in that case you might see exhaust fumes coming from one side.

The drainage hole is blocked on one side only , so water collects and then gets blown out the back.

On the dry side, the water dripped out as soon as it got there.