I don't buy Porsche for the better consumption Ev or Ice machine. I buy it for better solid feel and refinement + conering. It must somewhere to be trade off if an auto need better consumption (i.e thinner panels less sound proofing, etc). I only drive over 400km in a day twice a year.
Normal mode on city's driving. Range mode / sport mode on motorways. I did use 80% range mode 20% sport mode from Holyhead - London - Fortwilliam - Inverness. It worked out pretty good consumption as well as the handleing.
I wouldn't trade mine for a new one unless it has a big step forword (i.e battery techology.... guess will not happen in the next 4-5 years). Happy with my own present configuration.
It is expensive to own from new but cheap to keep it for a while. I keep good car for long unless it is a problematic one. My advise is do not buy a luxury car if you can't afford this type of depreciation.