Troubleshooting

What you see	Why	What to do
Part of the vehicle (or all of it) is invisible; only wheels and seats show	that mesh is over Vextris's limits and was refused (Rejected mesh in the log)	run the checker to see which; move parts to another mesh of the same atlas (e.g. <name>_front) or thin out what is hardly seen
duplicate part name in the log	two parts of one mesh share a name	use the latest export script (objects of one name are merged)
A line or a piece left across the door opening	a jamb, seal or window that moves with the door is on the body	parent it to the door's Empty in Blender
Badges and button symbols are noise	the decals' transparent parts were baked as colour	name them *_decal and use the baking script (it bakes alpha)
Panels crumpled, grilles broken into triangles	the whole car was decimated evenly	never decimate the outside; thin out only engine and underside
Paint colours too dark	the paint areas are not white	name paint parts *_paint and use the baking script (it whitens them)
Glass is opaque	the glass's alpha was not set	run vehicle_atlas_fixup.py; glass part names must hold glass
Lamps do not light, or light up black	names do not match, or the lens baked dark	use the lamp names under Parts in Modelling; run vehicle_atlas_fixup.py
Bullets and arrows pass through	no hit hull, or an old one	python tools/build_vehicle_hull.py ...
Wheelspin pulling away, spins at a flick of the wheel	too much power on the rear wheels only, or on grass	turn on allWheel, tractionControl, stabilityControl; grip follows the ground, grass has seven tenths of asphalt's
The preview or the HUD silhouette shows another vehicle	an old Vettura	update