enum pInfo
{
    FuelAmount,
}

new PlayerInfo[MAX_PLAYERS][pInfo];

//This is how i give and take fuel
PlayerInfo[playerid][FuelAmount] = PlayerInfo[playerid][FuelAmount] -200;

PlayerInfo[playerid][FuelAmount] = PlayerInfo[playerid][FuelAmount] +200;

//etc etc etc

public OnPlayerConnect(playerid)
{
    new Playername[MAX_PLAYER_NAME];
    GetPlayerName(playerid,Playername,sizeof(Playername)); // Lets say your name is Johnny
    if(dini_Exists(Playername)) PlayerInfo[playerid][FuelAmount] = dini_Int(Playername,"FuelAmount");
    return 1;
}

public OnPlayerDisconnect(playerid, reason)
{
    new Playername[MAX_PLAYER_NAME];
    GetPlayerName(playerid,Playername,sizeof(Playername)); // Lets say your name is Johnny
    dini_IntSet(Playername,"FuelAmount",PlayerInfo[playerid][FuelAmount]); // FuelAmount in file Johnny contains now the amount of Fuel you have.
    return 1;
}

stock LoadPlayer(playerid)
{
    new pName[MAX_PLAYER_NAME], fstring[288]; //Idk why I am using 288 for files :S
    GetPlayerName(playerid, pName, MAX_PLAYER_NAME); //Get's a player name
    format(fstring, 288, "%s.ini", pName); //Format file "scriptfiles/USERNAME.ini".
    if(!dini_Exists(fstring)) return 0; //If the "scriptfiles/USERNAME.ini" doesn't exists. don't continue
    PlayerInfo[playerid][FuelAmmount] = dini_Int(fstring, "FuelAmmount");
    return 1;
}

stock SavePlayer(playerid)
{
    new pName[MAX_PLAYER_NAME], fstring[288]; //Idk why I am using 288 for files :S
    GetPlayerName(playerid, pName, MAX_PLAYER_NAME); //Get's a player name
    format(fstring, 288, "%s.ini", pName); //Format file "scriptfiles/USERNAME.ini".
    if(!dini_Exists(fstring)) dini_Create(fstring); //If the "scriptfiles/USERNAME.ini" doesn't exists, create it
    dini_IntSet(fstring, "FuelAmmount", PlayerInfo[playerid][FuelAmmount]);
    return 1;
}