Murray Missile 

I keep a couple 55 Gal. contractor bags under the driver's seat in the car. I've come across bikes for sale while away from home without my bike rack or have needed to transport a bike under adverse conditions such as those you listed. I am usually transporting 63cm road bikes and I can "just" fit them in the back seat of my car by removing the front wheel. A 55 Ga. contractor bag will fit over a 63cm road bike or 22 inch MTB from the rear just past the cranks with the seat and post removed or all the way down. Removing the pedals helps but more for getting it through the door and between the seats, normally the bag will clear the pedals but it can be a struggle on a breezy day LOL. Smaller frame sizes are pretty easy. The bags also come in very handy when you have to change a tire in the rain, you can make an emergency poncho out of one by cutting arm holes and an opening to get it over your head and put the other bag down to keep the mud off your pants.

Chris!

Step one and this is the most important for survival. Relocate before partner sees what you've done to the car.
step 2 buy a new bike with the savings from your new lifestyle.

Wanderer

Lighter fluuid or straight naptha, is what the undercoaters use, and it works.

rsbob 

Method used: Napa brake cleaner and upholstery attachment on carpet cleaner machine with carpet cleaning solution. After cleaning the area, it came out so well I used the machine to do the rest of the interior. Currently have a fan on the treated area to help dry out the brake cleaner smell, before my wife holds her nose. Thanks for all the suggestions.

before:




After:

AlanO

If it matters to you just take it to a detailer and give him $20. If you start trying random things you risk permanent discoloration.

BillWest1974

Resolve carpet cleaner works well. I have curtailed that problem br buying a moving blanket for the back of my suv. Because of the built-in backup camera on the suv, I can't mount a bike rack.

Milton Keynes

I spilled spot remover on my dog, now he's gone.

alanf

A little too late but here is my solution...

I also have a plastic bubble wrap cover cut out to cover the floor and then a cheap polyester blanket over that for my Rav when I fold the seat down.
I have an '07 and the floor is in excellent shape considering all of the junk I carry in there periodically.

veganbikes

I don't know for carpeting but the Rock "N" Roll Miracle Red works fantastically on my Khaki shorts because they are comfortable and I enjoy wearing them but of course in the day of working at a shop even doing mostly sales I will come across some grease. It really does work with a little scub-a-dub-dub.

gene99

[QUOTE][Lighter fluuid or straight naptha, is what the undercoaters use, and it works./QUOTE]

yeah, b/c after you light the match you'll forget all about the rug.

BikeOnForever

I've found the quickest and best option is MEK - Methyl Ethyl Ketone, available at Home Depot or Lowe's. Douse a clean rag in MEK and the grease just melts off. Doesn't even leave a dirty residue. Repeat if necessary. Dries very quickly. Don't use on the headliner because it'll break down the adhesive holding the fabric to the headliner backing. Also, it's very volatile so no open flames nearby. Preferable use it outside.

Another good option is nail polish remover. Usually nail polish remover is Acetone (Dimethyl Ketone), a close relative of MEK. MEK works a little better but Acetone will do the job too. Just make sure the acetone or nail polish remover you use is not colored, otherwise it'll leave that color residue on the carpet. Good luck!