Or maybe your children, a friend?..  In any case, you clean it up as fast as you can, you even shampoo it with the latest in carpet cleaners, drive the rest of the day with everything smelling fresh and clean. 

But the next morning, you go to get into your car and Ugggg!  that lovely smell hits your nostrils.  But you cleaned and cleaned it yesterday?..   So you roll down the windows and drive to work and sort of get used to it, or hope that the fresh air will deal with it, you forget about it... only for it to happen again the next morning.

Vomit smell is hard to get out of any carpet, but a car is that much worse because you leave it closed up, with no air flow, and the sun is beating down on the car and it heats up, and the smell hits you again.

Here is a simple trick, but you have to remember to do this the night before for it to work.  Get a bowl and fill it up with vinegar and place the bowl on the floor of your car, and then close your car up for the night.  Only do this, when you know you won't need the car again until the next day.

But don't forget to take the bowl out of the car the next day, you don't want to be wearing the vinegar as your new perfume or aftershave. 

You should notice that the smell has been neutralized, this works for any smells in the car, but especially works well for vomit smells and odors.