The dry ice didn't work all that well for me, maybe I did it wrong or it was too hot. I bought about $30 worth and let it sit before hitting with a hammer/scraper. I broke up the dry ice and used some direct and some in a big zip loc. It works okay at first on the flat spots, difficult on vertical areas.

It took me a full day to do my car, most of it I ended up using a propane torch on. Not fun, but it works. Heats up real quick, then easily scrapes with a putty knife. Mineral spirits made a big mess on clean-up, instead a wire cup wheel on a small grinder was perfect. I went through about 3 wheels, be prepared to get dirty.

 

Dry ice worked great for me. I used a lot of it. Got it from AirGas. The more you use the easier it was, seems like. Break it up and let it cover the entire area, you can also put it in a paper bag to do vertical areas. Then used chemicals as poster above did. Some areas you just have to scrape off.
Probably a combo, of dry ice, scraping and wire cup/grinder will get it done.

This is what it looks like now.

 

I used the dry ice and air chisel method on my 3rd gen. I bought 12-15 lbs twice, about 2 hours each time. 17 lbs

 

more is more when using dry ice. If you can, get your car up on jack stands as high as possible and use a dead blow on the under side of your floor pan all 'whack a mole' style. That seemed yield the best results for me.

 

I found that if you take large pieces of dry ice and, while wearing a heavy leather glove (preferably a welding glove) hold it in one spot for ~30 seconds, remove and instantly hit with a hammer. You can control where the cold is, so you can concentrate on one area and not have to worry about all the other dry ice vaporizing before you can get to the other areas. I did it on my first FB, and netted about 20 pounds.

 

We took about 25lbs out of my FC race car. We only got maybe 85% of it out. The stuff on the upright metal like on the trans tunnel is tough to get out because its hard to get the dry ice to just sit on there like on the horizontal surfaces.

Dry ice worked like a charm! I was thinking of trying liquid nitrogen...not even sure where to get it though.

 

Buy 40 lbs (people make the mistake of nit buying enough)

Mote is better!

Break about half of it into small chunks & spread it on the flat surfaces & cover it with some cloth (I used old shirts, and pairs of pants) Tgis helps to prevent evaporation & isolate the cold.

Keep the otger bigger chunks for the vertical applications.

Let ice sit for approx 7-10 minute.

Get below the car & shock the floor pan with a rubber/ rawhide mallet.

It's easier if your car is on hack stands.

After you hear the crackling if the tar/ metal is when you should shock it, this will almost entirely separate the two surfaces.

Scoop up the chunks off the floor & use a spatula/putty knife to help separate the tar from the chassis surface.

If done properly, the tar can be removed as 1 piece.

 

The tricky areas are where it has fused itself with seam sealer. I just use brake cleaner...