26 USC 4002 - 1st retail sale; uses, etc. treated as sales; determination of price

(a) 1st retail sale 
For purposes of this subchapter, the term 1st retail sale means the 1st sale, for a purpose other than resale, after manufacture, production, or importation.
(b) Use treated as sale 

(1) In general 
If any person uses a passenger vehicle (including any use after importation) before the 1st retail sale of such vehicle, then such person shall be liable for tax under this subchapter in the same manner as if such vehicle were sold at retail by him.
(2) Exemption for further manufacture 
Paragraph (1) shall not apply to use of a vehicle as material in the manufacture or production of, or as a component part of, another vehicle taxable under this subchapter to be manufactured or produced by him.
(3) Exemption for demonstration use 
Paragraph (1) shall not apply to any use of a passenger vehicle as a demonstrator.
(4) Exception for use after importation of certain vehicles 
Paragraph (1) shall not apply to the use of a vehicle after importation if the user or importer establishes to the satisfaction of the Secretary that the 1st use of the vehicle occurred before January 1, 1991, outside the United States.
(5) Computation of tax 
In the case of any person made liable for tax by paragraph (1), the tax shall be computed on the price at which similar vehicles are sold at retail in the ordinary course of trade, as determined by the Secretary.
(c) Leases considered as sales 
For purposes of this subchapter
(1) In general 
Except as otherwise provided in this subsection, the lease of a vehicle (including any renewal or any extension of a lease or any subsequent lease of such vehicle) by any person shall be considered a sale of such vehicle at retail.
(2) Special rules for long-term leases 

(A) Tax not imposed on sale for leasing in a qualified lease 
The sale of a passenger vehicle to a person engaged in a passenger vehicle leasing or rental trade or business for leasing by such person in a long-term lease shall not be treated as the 1st retail sale of such vehicle.
(B) Long-term lease 
For purposes of subparagraph (A), the term long-term lease means any long-term lease (as defined in section 4052).
(C) Special rules 
In the case of a long-term lease of a vehicle which is treated as the 1st retail sale of such vehicle
(i) Determination of price The tax under this subchapter shall be computed on the lowest price for which the vehicle is sold by retailers in the ordinary course of trade.
(ii) Payment of tax Rules similar to the rules of section 4217 (e)(2) shall apply.
(iii) No tax where exempt use by lessee No tax shall be imposed on any lease payment under a long-term lease if the lessees use of the vehicle under such lease is an exempt use (as defined in section 4003(b)) of such vehicle.
(d) Determination of price 

(1) In general 
In determining price for purposes of this subchapter
(A) there shall be included any charge incident to placing the passenger vehicle in condition ready for use,
(B) there shall be excluded
(i) the amount of the tax imposed by this subchapter,
(ii) if stated as a separate charge, the amount of any retail sales tax imposed by any State or political subdivision thereof or the District of Columbia, whether the liability for such tax is imposed on the vendor or vendee, and
(iii) the value of any component of such passenger vehicle if
(I) such component is furnished by the 1st user of such passenger vehicle, and
(II) such component has been used before such furnishing, and
(C) the price shall be determined without regard to any trade-in.
(2) Other rules 
Rules similar to the rules of paragraphs (2) and (4) of section 4052 (b) shall apply for purposes of this subchapter.