By Randy Ellis Staff Writer rellis@oklahoman.comThe Oklahoma Automobile Dealers Association has filed a state Supreme Court lawsuit challenging the constitutionality of a new 1.25 percent sales tax on Oklahoma motor vehicle purchases. The new sales tax was approved by the Oklahoma Legislature during its most recent session and is scheduled to take effect July 1. The automobile dealers contend House Bill 2433 amounts to a tax increase.Read more on NewsOK.com