[shady91]

pawn Код:

new Spawned[MAX_PLAYERS];//global varible

pawn Код:

Spawned[playerid] = 0;// add under onplayerconnect

pawn Код:

if (strcmp("/nrg", cmdtext, true, 10) == 0)
{
if(Spawned[playerid] == 1)
{
SendClientMessage(playerid, yourcolor, " You already spawned a nrg500");
retrun 1;
}
        new Float: X, Float: Y, Float: Z, Float: A;
        GetPlayerPos(playerid,X,Y,Z);
        GetPlayerFacingAngle(playerid,A);
        new car = CreateVehicle(522,X,Y,Z,A,-1,-1,120000);
        PutPlayerInVehicle(playerid,car,0);
             Spawned[playerid] = 1;
        return 1;
    }

not tested should work tho