someone accidentally spilled soda all over the floor of my car and am wondering what is the best way to clean?

Use an oxy clean. Use spot shot if there is a stain remaining

Put some baking soda over the spill and then add a little water to it. Then wet the bristles of a carpet cleaning brush and scrub it. I would put it on there and let it sit for a few minutes, then use the brush. Also, Resolve Carpet Cleaner works well for puppy pee stains so I'm sure it will do just as good with soda. Same thing with this, spray it on, let it foam and sit for a few minutes, then use a brush and scrub it out.