probably because I always take the standard mileage deduction)
That's exactly why the 4562 is not sent to the IRS. While you may have the vehicle listed on the 4562, that form will show $0 depreciation for that vehicle, because the depreciation is already include in the per-mile deduction.
The disposition of the old vehicle doesn't show up
If you correctly reported the disposition of the old vehicle, then most likely it doesn't show up where you expect it to. Did you report the vehicle as traded in for the new one? Or did you report it as it's own separate sale of the vehicle asset?
FYI, to see the amount of each year's per-mile deduction back to 2003 that is depreciation, see https://bradfordtaxinstitute.com/Free_Resources/IRS-Mileage-Rates.xml.aspx and scroll a bit more than halfway down the page for the table.
