Is this really due to Hertz's electrification efforts, or just a broader trend (ie. lockdowns ending leading to more car rental use)? If we look at their competitor, we see that their profits rose even more (in percentage terms)[1]. Sure, being "50-60% cheaper to maintain" is nothing to sneeze at, but without analysis into how much that weighs against other factors (eg. depreciation, because electric cars are more expensive) making such bold claims is simply irresponsible.
I'm also thinking about depreciation. I suspect most people that want an electric car are going to buy new, especially considering the tax credits. Are they going to be able to successfully offload 3-year old, high-mileage rental electric cars?