So yesterday and today were the two coldest days of the year so far. 3 degrees F. or -16 C. Our Niro Hybrid is parked in a garage so my starting temperature was close to the freezing point until I pulled outside.
Yesterday, by the time I reached my destination (9 kilometers or 5.6 miles away), my fuel consumption was 8.1 liters per 100 kilometers
and the Internal Combustion Engine had been running the entire trip, as were the heated seats and heated steering wheel. According to the instrument panel display, the engine had reached Full Operating Temperature by the time I reached my destination and the interior heat vents (Driver Only) were blowing VERY hot air. Also, my blue battery state of charge indicator was the highest I'd ever seen it at about 90% AND the Energy Flow Display indicated that the engine was no longer charging the battery, just powering the drive wheels directly, although Regen still appeared to function according to the instrument cluster display. The gasoline engine did stop immediately when I turned the heater off.
Today, I repeated the same trip and managed 6.1 liters per 100 kilometers
. So what were the differences? I only activated the heater when travelling downhill and/or the Yellowish Orange INSTANTANEOUS Fuel Consumption Bar indicated I was using less than 5 liters per 100 kilometers. Also, under these conditions, the Energy Flow Display indicated that the Internal Combustion Engine was NOT powering the wheels directly but flowing to the motor/generator, then back out to the wheels whilst also charging the battery. I'd never noticed that before. As soon as that display indicated that the engine was powering the wheels directly, (and the battery state of charge was high), I shut off the heater until the engine started again anyway to recharge the battery. Obviously the heated seat and steering wheel were much appreciated during the early stages of the trip. I also discovered that I could actually achieve what appeared to be lower instantaneous fuel consumption by switching to SPORT mode and manually shifting to the highest gear it would allow (6th gear was achievable by 60 kph) with the engine virtually idling. In NORMAL mode, the vehicle seemed to be automatically holding on to a lower gear with the attendant higher revs, presumably to achieve faster warm-up.
I also discovered about a week ago, when the temperature was about -5 Celsius or 23 Fahrenheit, that running the heater causes VERY little fuel economy degradation on a long trip after the engine has reached full operating temperature. The gasoline engine is going to cycle anyway so rather than exhausting heat out the front radiator, we might as well use it to heat the cabin and then turn off or lower the heated seats and steering wheel to reduce electrical load. On a 225 kilometer round trip with a few stops, including one complete 2 hour cool-down period, we achieved 4.9 liters per 100 kilometers on dry roads. That same trip in the summer time would have yielded about 4.6 litres per 100 kilometers, so not much of a hit to stay warm. To be fair, I'm running 205/60/16 Michelin X-Ice Winter Tires as opposed to the 225/45/18 Michelin Summer Tires, and narrower tires are supposed to be more efficient.
It's those short trips in winter that can eat into mileage pretty dramatically
. At any rate, if approximately 8 liters per 100 kilometers is the WORST I'm likely to see, that's still more than double the fuel economy I can expect out of our other ICE vehicle under similar conditions. I can live with that. In the summer months, the Niro is nearly 3 times more efficient in the city but only about 1.6 times more efficient at highway speeds. Once I get that 4,600 pound ICE vehicle rolling it does pretty well but getting it moving in the city takes a lot of fuel, plus the complete waste while sitting idling at stoplights.