Spilled VERY sour milk in car

On Sunday an 8 year old passenger put a grocery bag with a 1/2 gal milk container on the back seat of our van, which she removed on being transferred to her mother’s car. Not until Tuesday did I ge in the car again. It smelled like spoiled cabbage or a decomposing body. After a thorough search I found escaped from historic grocery bags, a jar of jam under the driver’s seat and an onion wedged under the front of the back seat. Neither smelled. Going to the “trunk” area, we emptied all the carried around junk, the bottom layer of which had a milkish look, and it overwhelmed our olfactory nerves. I googled what to do, and got a 7 step plan, the last step of which was to “Hire an expert”. We’re on step 4 as of today, and it still smells pretty bad - only not quite as strong. What we’ve done: Day one - Wet vacuued (with our deep cleaning vac) then sprinkled ample amounts of baking soda over the areas involved, followed by a layer of cold water and waited overnight. Day 2 - Wet vacuuuued and sprinkled with vinegar and waited overnight. Day 3 - Wet vacuued and sprinkled more baking soda and then a layer of cold water and are waiting until tomorrow to vac again. We’re thinking of going with another round of vinegar tomorrow, or maybe going on to Step 5, which is “household carpet cleaner over the area where the milk was spilled or all over the car’s upholstry and carpeting if the smell is strong throughout the car”. (which it is) and “Leave the cleaner on the upholstry for the length of time specified on the package, then vacuum it out.” This is hot and smelly work down here in Alabama in August, and we’d just like some second opinions on whether we should keep daily alternatings of Baking soda and vinegar or give up on that and go on to carpet cleaner - for several times, or is there some magic solution google didn’t know about. I didn’t see how much milk was in the bottle initially. It did look like about a quart as she carried it off. This is a minivan with a sunken floor rear compartment, which to my imagination may be harboring unreached milk between the carpet bottom and the frame top… Its carpet is securely glued/stapled to the frame, so we can’t do step 3, which was to remove floor mats and seat covers and wash separately. All help will be appreciated and tried - I guess until we wear through the car insides.

The carpet is not glued down and can be removed, and that is pretty much what you are going to have to do.

You could also take it to a detailing shop near you and let them deal with it. That will cost more money, but it might be an attractive alternative if you can afford it and don’t have much time on your hands.

All of the above .
What are you vacuuming with ?
For all my deep down spills I use my 8gal wet/dry shop vac and very hot water.
This super strong ( think golf ball through a garden hose ) vacuum will get it up from deep down inside. And that’s where it went, down in the matting and pad that you never get to see.
This is why you need to take out the carpets and pad,s giving top and bottom sides the treatment and vacuuming.
with the carpets out you get to clean the steel too, a part we really never get clean from the top.

My 91 Explorer was purchased used and had a persistant dog barf smell in the back.
These methods were needed to get that too.

Agree with others. I would have gone with the carpet cleaner right away. Don’t think baking soda is going to do much. In the meantime it contiues to rot. I usually mix up a solution of carpet steam cleaner and get it good and wet and wet vac it and repeat. But until you get the carpet out and clean up what’s underneath and the whole carpet including the backing, you aren’t going to get it all.