Approx how much would it cost to replace all carpeting, the backseat, interior of trunk, jack, tool bag, spare tire, etc. in a 2005 dodge neon sxt? I was unfortunate enough to spill 4 gallons of oil in the trunk and it went underneath all upholstery.

Wow, that is unfortunate. I had a Neon back in 99 for 16 months and I hated it. I drove through a hurricane and was hoping it would get caught in an overflowing creek and I could get out and it would be washed away. Well, that didn't happen. Let me ask you, was this used motor oil or unused motor oil? I think it would be disgusting to have a car with dirty motor oil spilled in it. Probably would smell. Maybe you will be lucky enough to have someone plow into this car if you park it in a dangerous spot.

You may want to find a junk yard that had the same car before it is cut up. Carpets are usually not saved but if you tell them in advance and are lucky enough to get a place that has some mercy you may save some money. All new would be very expensive unless you find it aftermarket.