Tex. Occ. Code § 2301.468

Notwithstanding the terms of a franchise, a manufacturer, distributor, or representative may not treat franchised dealers of the same line-make differently as a result of the application of a formula or other computation or process intended to gauge the performance of a dealership or otherwise enforce standards or guidelines applicable to its franchised dealers in the sale of motor vehicles if, in the application of the standards or guidelines, the franchised dealers are treated unfairly or inequitably in the sale of a motor vehicle owned by the manufacturer or distributor.