You couple's creative tax-cutting doesn't go with IRS

Nah, your car, furniture, jewelry,...are not investment instruments.

Your primary residence is half way: if you make money selling it, you pay tax; if you lose money, you can't deduct the loss.

Now, if you use your car to earn money (say getting paid for driving your neighbor's kids to school) you can deduce the depreciation, GIVEN THAT YOU REPORT THE MONEY EARNED.