An empty vehicle will not fall after being teleported into the air.
(vehicleid, Float:x, Float:y, Float:z)
vehicleid
Vehicle ID that you want set new position.
Float:x
The X coordinate to position the vehicle at.
Float:y
The Y coordinate to position the vehicle at.
Float:z
The Z coordinate to position the vehicle at.
// Put the player's vehicle at the coordinates 0, 0, 3 (center of SA)
new vehicleid = GetPlayerVehicleID(playerid);
SetVehiclePos(vehicleid, 0, 0, 3);
The following functions may be useful, as they are related to this function in one way or another.