It refined it and also refined regions not "inside" of the geometry. surfaceFeatures didn't produce any errors. Surface refinement worked as it should. My only problem is the refinement regions using said STLs. To automate this, I use surfaceTrasnformPoints to create "shells" that are about 1.1-1.2x the height and width of the car but 2.5-3x the length to better capture the wake, and they are level 3 and 2 refined while the surface is level 5 and 4. At first, I thought this would be more economical than a hexahedral box hence the motivation to use this method (third image). The geometry looks fine to me. I believe it's good enough to use. These are the important bits from my snappyHexMesh dict (removed the rest because I'm running out of space otherwise) ⁨``` geometry { body { type triSurfaceMesh; file "body.stl"; } frontWheels { type triSurfaceMesh; file "frontWheels.stl"; } rearWheels { type triSurfaceMesh; file "rearWheels.stl"; } LOD3 { type triSurfaceMesh; file "LOD3.stl"; } // shell for level 3 refinement LOD2 { type triSurfaceMesh; file "LOD2.stl"; } // shell for level 2 refinement } castellatedMeshControls { features ( { file "body.eMesh"; level 5; } { file "frontWheels.eMesh"; level 5; } { file "rearWheels.eMesh"; level 5; } ); refinementSurfaces { body { level (4 5); patchInfo { type wall; }; } ".*Wheels" { level (4 5); patchInfo { type wall; }; } } refinementRegions { body { mode distance; levels (($distL5 5) ($distL4 4)); } ".*Wheels" { mode distance; levels (($distL5 5) ($distL4 4)); } LOD3 { mode inside; level 3; } LOD2 { mode inside; level 2; } } insidePoint $safePoint; } ```⁩ I'd be happy to provide any logs or files that could help. https://cdn.discordapp.com/attachments/397874745464586242/1468730598699831619/image.png?ex=69851576&is=6983c3f6&hm=63cf7d55b630df01c1a6b1ceb00623d3f2a70f7face9c635b097e1d113e5b173& https://cdn.discordapp.com/attachments/397874745464586242/1468730599090032672/image.png?ex=69851576&is=6983c3f6&hm=726644212b7d27eb1ac12b868422e886043d9aa20bb504adc9b97ae25324f1eb& https://cdn.discordapp.com/attachments/397874745464586242/1468730599442223205/image.png?ex=69851576&is=6983c3f6&hm=0fb4e76a750e26e64c543f61c6be561032b9e6be0fb5cb123c6310a00dccc0df&