[JhnzRep]

pawn Код:

public timer_fuel_lower()
{
    new engine, lights, alarm, doors, bonnet, boot, objective;
    for(new i=0;i<MAX_Vehicles;i++)
    {
        GetVehicleParamsEx(vid, engine, lights, alarm, doors, bonnet, boot, objective);
        if(engine == 1)
        {
            fuel[i] -= 1;
        }
    }
    return 1;
}

Edit:

Then you can make a function to show the player the current fuel

pawn Код:

public ShowGas()
{
    new str[15];
    new engine, lights, alarm, doors, bonnet, boot, objective;
    for(new i=0;i<MAX_PLAYERS;i++)
    {
        if(IsPlayerInAnyVehicle(i))
        {
            if(fuel[GetPlayerVehicleID(i)] == 0)
            {
                GetVehicleParamsEx(GetPlayerVehicleID(i), engine, lights, alarm, doors, nonnet, boot, objective);
                SendClientMessage(i, -1, "Your car ran out of fuel!");
                SetVehicleParamsEx(GetPlayerVehicleID(i),  0,  lights, alarm, doors, bonnet, boot, objective);
            }    
            format(str, sizeof(str), "Fuel:%i",  fuel[GetPlayerVehicleID(i)]);
            GameTextForPlayer(i, str, 3000, 3);
        }

}

Should do it.