We just lost our engine on a 2012 Hyundai Accent. We never had the engine light come on or any smoke to indicate a low engine oil or leak. But the engine eventually came on and started knocking. We towed it and noticed it had a quart of oil in the engine. The car is cleaned. No indication anywhere of lost oil. My question is can a car run for 4600 miles with a quart of oil? It's a mystery as to where the oil went. I'm thinking when we took it to Kwik Kar they failed to put oil in it or not enough. They are not owning the responsibility because they say a car cannot run that long with no oil. I say "where did the oil go?" Any ideas? Thanks.
If you take a look at this answer on another question related to oil, you can see that the oil light means that there is no oil pressure, and doesn't have anything to do with the level of oil.
That said, one quart is very low, and probably not enough to circulate through the engine. I guess it's possible that you did have oil pressure and a normally lubricated engine, but not likely. The oil pressure light should have come on to warn you about this serious condition. Note that oil pressure is normally a separate red light than using the same orange check engine light. Red lights need immediate attention.
The oil had to go somewhere. Either they drained it and didn't properly fill it back up, it was burned in the engine (making smoke), or it leaked (making a mess).
All vehicles consume some oil. How much depends on the specs of the engine and it's condition. A quick google search suggests others have experienced a quart per 1000 miles. That's a lot, but it's not unheard of. If your engine had bad piston rings or valve seals, you could be burning a large amount without ever noticing.
As mentioned, the oil light is for oil pressure. I would expect it would notify you of the problem once the oil dropped to a level below the pickup, but you don't have a lot of time once it comes on to kill the engine and prevent serious damage. That level is also well below what an engine needs to clean and cool the engine properly.
It's possible for the pressure sensor to stop working (although that usually results in a false positive) or for the bulb in the dash to burn out, especially if it's not an LED. When you first turn the key to the ON position, you should see the entire dash light up and confirm that all the lights are working. You can do this to check that the oil pressure light is capable of coming on.
The the oil pressure light is an emergency warning, and shouldn't be used as a replacement for checking the engine oil level regularly.