Taotao USA, Inc. (“Taotao USA”), Taotao Group Co., Ltd. (“Taotao China”), and Jinyun County Xiangyuan Industry Co., Ltd. (“Jinyun”) (collectively referred to as “Appellants”) appeal from an Initial Decision that Chief Administrative Law Judge (“ALJ”) Susan L. Biro issued holding these companies liable for violations of the Clean Air Act’s (“CAA”) mobile source program and assessing a civil penalty. The U.S.