Try washing the area really well with warm water, white vinegar and bicarbonate of soda. And is there a place where you can leave the car with the windows open to air it out? Once the fabric and carpet is dry try sprinkling a lot of bicarbonate of soda over the area, leaving it for maybe a day and then vacuum it out. If you have to use an airfreshner I find Neutradol is very good - and you could even use Febreeze on the fabrics.
Mix one part soap to 1/4 part ammonia in warm water , and then wash the carpet - BUT do test a corner of the carpet first to make sure that the colour does not change ,if its ok proceed to do the whole carpet .
My daughter regularly used to get car sick and I found that the best way to get rid of the smell was to clean up the mess with diluted Dettol. Your car will smell of Dettol for a few hours, but this will disappear. Believe me it works,even after the car has been in the sun for a few hours!
clean up as thouroughly as possible,(obviously) Disinfectant mixed with washing up liquid is good for this. When its dry, sprinkle over bicarbonate of soda heavily on the area. leave over night if possible, then vacuum up