Yes, when you say "yes" to that screen it stops. That means you need to report the actual sale elsewhere, such as the "Sale of Business Property" section.
Yes, for purpose of the sale, the purchase price and average percentage can matter. For purposes of calculating a LOSS, you use the FMV, but for purposes of calculating a GAIN, you use the actual cost (and average life percentage).
However, with the numbers that you have shown, I can pretty much see the results without it ... you have $0 gain/loss. Because it will be a $0 gain/loss, I would just say the vehicle was converted to personal use, and not report the sale at all.
