The frame: VehicleLayout

In a pack: the layout section of vehicles/<name>.json, the fields as below (Java: new VehicleLayout.Builder(), fill it in, build()). Vehicle frame (forward, right, up) except where it says model frame.

Field	Meaning
body	the parked collision boxes (stand on the roof, get blocked by the car): a few Boxes in the car's shape
rainShell	what the rain stops on (RainPart: a box, optionally cut by a slanted plane; no cut: 0, 0, 1)
cabCushion cabFloor	the front cushions' top, the cab floor
seats	first the driver's, then the front passenger's: Seat(forward, right, cushion, yaw, look, inCab, right)
wheelX wheelY wheelZ	the steering wheel's hub (model frame)
columnY columnZ	the column's direction (model frame, the unit vector's Y and Z, into the dash)
rim	the steering wheel's radius
steeringRatio	steering wheel turn per road wheel turn
hingeX hingeZ	the door hinge (model frame; the sides mirror)
pull outer entry	the inside pull, the outside handle, where one stands to get in
shiftPivot shiftKnob	the gear lever's pivot and the knob's middle (model frame, upright in neutral)
exitF exitR	where one gets out
hood hoodUp	where the hood can be clicked, shut and open
door doorSwung	where the left door can be clicked, shut and open (the right mirrors)
filler fillNeck	where the filler door can be clicked; the fill neck

A pickup's bed, tailgate and transfer lever (bed, tailgate, transferPivot, ...) are simply left out.

Optional (without them, worked out from the boxes and points above):

Field	Meaning
exhaust exhaustOut	the exhaust outlets (several allowed: { {forward, right, up}, ... }) and the way the gas leaves. Without: one at the rear right, blowing back
engineVisible	the engine mesh (<name>_engine) is seen without opening anything (a mid engine's glass cover, an open bay): drawn whenever near. Without: only with the hood open
wiperY wiperZ	the wipers' axis (model y, z; about the windshield's normal). Without: the T15's windshield. For a strongly curved windshield, where turning about one axis lifts the blade off: wiperPoses, {"wiper_l": [[share, dx, dy, dz, qx, qy, qz, qw], ...], "wiper_l_blade": [...], ...}, the share rising from 0 to 1, each row the bone's move and turn at that share (a quaternion, model frame, about the bone's pivot), interpolated between
points	the prompts', sounds' and the two picking parts' places (VehicleLayout.Points); seldom needed

The tank's size is in the physics: b.tank = 73; (litres, 60 without).

These must agree with the Empties in Blender: the steering bone goes at Blender (wheelX, −wheelZ, wheelY).