[Patrik356b]

Slimmed:

pawn Код:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if(newkeys == KEY_SUBMISSION)
    {
        new vehicleid = GetPlayerVehicleID(playerid);
        if(vehicleid != 0)
        {
            new Float:angle;
            GetVehicleZAngle(vehicleid, angle);
            SetVehicleZAngle(vehicleid, angle+180.0);
        }
    }
    return 1;
}

As GetPlayerVehicleID will return 0 when player is not in any vehicle you can check vehicleid against 0 (zero) and omit IsPlayerInAnyVehicle
source: https://sampwiki.blast.hk/wiki/GetPlayerVehicleID