Check out Full Asset Race Track 3D Model Pack 3D model on CGTrader for $20. High-quality mesh by Round-Square.
STL (Stereolithography, filesize: 15.1 MB), OBJ (OBJ, filesize: 11.9 MB), FBX (Autodesk FBX, filesize: 28.4 MB), DAE (Collada, filesize: 20.1 MB), BLEND (Blender, filesize: 15.3 MB)