[Correlli]

I agree, this isn't really a bug. The game wasn't designed to put player from one vehicle to other.

But this function should fix it:

pawn Code:

stock PutPlayerInVehicleEx(playerid, vehicleid, seatid)
{
  new
      Float:playerPos[3];
  GetPlayerPos(playerid, playerPos[0], playerPos[1], playerPos[2]);
  SetPlayerPos(playerid, playerPos[0], playerPos[1], playerPos[2]);
  PutPlayerInVehicle(playerid, vehicleid, seatid);
  return true;
}