I have been helping a friend clean up a '65 Mustang and I found this link while searching for information on the Eastwood under coating removal kit.

http://www.svend.net/mustang/ww73/ww73.html

We found the Peel Away product at the local Lowes store. (The local HD and Menards did not have it.) Lowes had it in a quart for $15 and the sheet for $3. Based on what we used for two wheel wells you may be able to do all 4 wheel wells on a small car with a quart and pack of sheets.

We did most of the work outside. We started power washing the wheel wells letting that dry over night. We then painted the peel away on. Put the paper on and rolled it out with a old small paint roller. We then let it set for 48 hours.

We then rolled the car back out side and scrapped a lot of the under coating off with a putty knife. We followed up with another power washing. Dried it with a heat gun then followed up with a cone shaped wire wheel on a 4" grinder. Blew out the well wells with air gun to clean out the small pieces of under coating. Then we did a quick primer job to keep it from flash rusting.

All of this with out any toxic smells. It did take some work but not as much as other options I have read about. Some of those options could kill a person.

I still say paying someone blast the car is the best and easiest option but if you want to do it your self this is a close second.