Schreibe den Befehl mal so:
ocmd:opark(playerid,params[])
{
if(!IsPlayerInAnyVehicle(playerid))return SendClientMessage(playerid,COLOR_RED,"Du musst im Towtruck sitzen!");
new trailercar = GetVehicleTrailer(GetPlayerVehicleID(playerid));
if(!IsTrailerAttachedToVehicle(GetPlayerVehicleID(playerid)))return SendClientMessage(playerid,COLOR_RED,"Du musst ein Fahrzeug am Towtruck haben!");
GetVehiclePos(trailercar,PlayerAuto[trailercar][paX],PlayerAuto[trailercar][paY],PlayerAuto[trailercar][paZ]);
GetVehicleZAngle(trailercar,PlayerAuto[trailercar][paA]);
SendClientMessage(playerid,COLOR_GREEN,"Auto wurde nun hier abgestellt.");
DetachTrailerFromVehicle(GetPlayerVehicleID(playerid));
SetPVarInt(vkey,"towed",1);
format(str,sizeof str,"autos/auto_%d.txt",trailercar);
dini_FloatSet(str,"X",PlayerAuto[trailercar][paX]);
dini_FloatSet(str,"Y",PlayerAuto[trailercar][paY]);
dini_FloatSet(str,"Z",PlayerAuto[trailercar][paZ]);
dini_FloatSet(str,"A",PlayerAuto[trailercar][paA]);
return 1;
}
mfg. 
//Edit: Hatte ein i vergessen zu korrigieren 