Wow, 555 Wh/mile is a LOT. But then, 14.4km is a pretty short drive...and efficiency numbers on short drives are worse than longer ones because of start-up costs (getting battery to temperature, warming up cabin, etc). If you want to see really bad numbers, just back to the end of your driveway, sit there for 5 minutes with the car on, and then put the car back in the garage. (I am not complaining about your post or numbers; just clarifying for those unfamiliar). This is why "winter EV driving tips" often include preheating the car while still plugged in, and timing your charge to end right before you leave. Curious - did you do that, or are these numbers from a cold start?
Before I went electric I had a 2005 Honda Insight hybrid. I could get over 80mpg on long round trips, but mpg got as low as 40 on winter days doing a short commute to work. Stuck in bad traffic once, I got 35mpg. I eventually got a block heater, and then winter commutes were usually in the mid-50's (so I was using less gas, although of course I was using more electricity).
As for long drives (say, 150 miles or more) the worst I've seen in over a decade of EV driving was a 1/3 efficiency loss. I don't often drive in very low temperatures, but I do sometimes drive in very-near-freezing temperatures with lots of hills and heavy rain, which has a huge effect. (Try putting your car in neutral in heavy rain and see how far it coasts, vs when the roads are dry).
