What Tom P. and calgarydetail said
I've used it as an APC and it's OK for that, especially for jobs involving grease. But...
While it'll work OK as an APC, I'd reserve it for jobs where it's grease-cutting abilities make it the *perfect* choice rather than using it for jobs where it'll merely be an (expensive) OK choice.
For areas of the (regular body of the) car that get winter-nasty, I'd just presoak with regular shampoo using a foamgun and then use the foamgun in conjunction with a BHB to gently dislodge and flush away the potentially abrasive [stuff] that gets caked on during that time of year.
For upholsery, I'd use an upholstery/interior cleaner. Something that'll require a bit less rinsing than the TAW (greasy messes excepted).