Mass. Gen. Laws ch. 90D, § 21A: Motor vehicles or trailers; limitation on creation of sale or security interest

Section 21A. In the case of motor vehicles or trailers, notwithstanding any other provision of law to the contrary, a transaction does not create a sale or security interest merely because it provides that the rental price is permitted or required to be adjusted under the agreement either upward or downward by reference to the amount realized upon sale or other disposition of the motor vehicle or trailer.