"good" in what way? Once the charging process is complete (at ~80% full) the car will use the energy in the battery until it's dropped a few percentage points and then recharge it again (referred to as a 'hysteresis' cycle). Without charge mode selected, exactly the same thing happens but with the battery 'empty' (in reality, ~15% charge left). Selecting save mode does the same, but at whatever level of charge is present when you press the button.
As long as you remember to turn charge/save mode off and arrive at your destination with the battery 'empty', you'll consume very similar amounts of fuel, whichever strategy you adopt.
