If it meets the federal definition of a handgun, it's a handgun (unless TN has some exclusions). The question I guess I'd ask, is what the hell are you gonna hit with an AK pistol? I think a more appropriate car gun is an 870 Marine Magnum or something along those lines.
US Code Title 18 Part 1 Chapter 44 Section 921
(a) As used in this chapter—
(29) The term “handgun” means—
(A) a firearm which has a short stock and is designed to be held and fired by the use of a single hand; and
(B) any combination of parts from which a firearm described in subparagraph (A) can be assembled.
Code of Federal Regulations Title 27 Chapter II Subchapter B Part 478 Subpart B Section 478.11
When used in this part and in forms prescribed under this part, where not otherwise distinctly expressed or manifestly incompatible with the intent thereof, terms shall have the meanings ascribed in this section. Words in the plural form shall include the singular, and vice versa, and words importing the masculine gender shall include the feminine. The terms “includes” and “including” do not exclude other things not enumerated which are in the same general class or are otherwise within the scope thereof.
Handgun.
(a) Any firearm which has a short stock and is designed to be held and fired by the use of a single hand; and
(b) Any combination of parts from which a firearm described in paragraph (a) can be assembled.
Pistol.
A weapon originally designed, made, and intended to fire a projectile (bullet) from one or more barrels when held in one hand, and having (a) a chamber(s) as an integral part(s) of, or permanently aligned with, the bore(s); and (b) a short stock designed to be gripped by one hand and at an angle to and extending below the line of the bore(s).
Revolver.
A projectile weapon, of the pistol type, having a breechloading chambered cylinder so arranged that the cocking of the hammer or movement of the trigger rotates it and brings the next cartridge in line with the barrel for firing.
Semiautomatic pistol.
Any repeating pistol which utilizes a portion of the energy of a firing cartridge to extract the fired cartridge case and chamber the next round, and which requires a separate pull of the trigger to fire each cartridge.