Deductions & credits

I came up with the $0 sale price from someone asking a similar question and a resulting TurboTax response. 

The link that you provided doesn't seem to function,  but the way that I  understand it, I am to calculate the Depreciation Equivalent since I did use the standard mileage deduction.  When I calculate that for the 8 years of business use, it's greater that the purchase price.   So I just enter the purchase price since TurboTax says the entry cannot be higher than the purchase price?

Using the percentage of business mileage, 48.24% of total annual mileage during the life of the vehicle where the deduction was taken, that same percentage of the total sale price is the gain?  $4000 x .4824

Lastly how is a Gain/Loss Basis calculated?

Thanks for the response!