True, there is buffer. Where a Tesla (supposedly), let's you charge each cell to 4.2V, on the e-Golf 35.8 kWh pack, the 100% SoC voltage is 4.1 V. If you read the scientific literature that looks at cell cycling and degradation rate, by charging to 3.9 V instead of 4.2 V, the cycle life of the cell is increased by about 10 times before showing the same amount of degradation (~5000 cycles vs ~500 cycles), and these studies usually look at full battery cycling from the max chosen SoC to a very low SoC like 5% or 10%. You will also get increased cell life if you keep the lower end to 20% or better most of the time. Of course, if you only charge up to 3.8 V, there is a further fold increase in cycle life, and yet more cycle life at 3.7 V. But as was already mentioned, what are you willing to live with on a daily basis? 80% is 3.94 volts, by my measurements, so I charge to 80% routinely and am comfortably able to get 80-90 miles of range and still have about 30% SoC left.
