In the case of motor vehicles and trailers, notwithstanding any other provision of law, a leasing agreement involving a motor vehicle or trailer shall not create a sales transaction or a security interest in the vehicle merely because the lease contains provisions which provide that the rental price is permitted or required to be adjusted under the agreement either upward or downward based upon an amount which may be realized from a sale or other disposition of the vehicle after the end or termination of the lease period.