You pays the taxes on the M3, he pays taxes on the RX7.
http://dmv.ny.gov/forms/dtf802.pdf There’s the form.
Section 5, question 1c.
“c. Value of property given, traded, or swapped, or services performed instead of cash payment…”
You sure the vehicles aren’t each worth $5,000 due to some body damage or improper running? (hint, hint)