I did a little fuel economy testing today. The weather was a bit less than 20 degrees F, and the sky was overcast, so no heat from the sun. Pretty typical winter weather in my area. I needed to go to a store about 17 miles away. I figured that's within my range, and it wasn't crazy cold, so I could do some testing without risk of not getting home or other problems.
I pre-heated the car from the wall power with the pre-heat feature for about 10 minutes before I left.
I was wearing "normal" winter clothing - coat, hat, gloves, but NOT an extra sweatshirt, long underwear, etc. The type of clothing a person would expect to wear while going in and out of buildings from a car, but not spend an hour outdoors in. During the trip, I wasn't cold. I certainly wasn't sweating either. The heater was doing it's job of making me not freeze, and allowed me to keep the electric heat off.
Also, the trip to that store takes about 30 minutes, and that's the default run time on the fuel-heater controller. I ran the fuel-burner and set the fan to blow with the temperature control set to neutral. When I got to the store, the heater had just stopped running. I popped the hood and took a photo of the gas tank. It was a little more than half-full. I don't remember my exact battery charge, but it was definitely more than half full.
In case it's a little hard to see, here's an image with a red line added at the level of the fuel.
I did some shopping for probably 45 minutes, then returned to the car, fired up the heater, and headed home. I also had to stop at the bank (where I let the heater keep running,) and the 30 minute timer on the heater was up as I arrived at another store, just a couple miles from home. Again, I lifted the hood and took a photo of the fuel tank. This time, the fuel was much lower, so I took the photo at more of a side angle.
Again, if that's hard for you to see, here's one with a red line added for your viewing pleasure.
And yes, that is a zip-tie, and yes the fuel tank IS secure. I did NOT have an accurate way to measure what fuel is left. Potentially, I could have just run the heater again and set a timer, and checked the timer when fuel ran out. At least that way, I would have a known total run time based on that one liter of fuel.
As it is, the second photo shows how much fuel was used up after an hour of heating (two 30 minutes heats.)
The manual says that on gasoline, the heater uses 0.69 liters per hour in the HIGH mode. I don't think that the heater ever swtiched down to the low power mode while I used it today. Also, it looks like I used more than .69 of a liter. My best guess looking at the fuel tank it that I used closer to .85 or .9 liters in that one hour burn time. I was running E85, and I know that when used to power an engine, fuel economy usually drops about 20-25%.
E85 has about 71-72% the theoretical heat energy content compared to gasoline.
0.69 l/hr divided by 72% = 0.958 liters per hour.
And all this time, I was just GUESSING about a liter per hour.
The trip was 35 miles total. I was using the freeway most of the that, going about 60 miles per hour. I did see a Nissan LEAF on the freeway on the way home, which was cool. Seeing a LEAF in my area is rare. I had 13 miles left on the range-o-meter when I got home. Actual miles traveled plus R.R. comes to 48 miles. I started with a full charge, but was mostly on the freeway, (and it's winter,) so numbers lower than the EPA 62 are expected. It always amazes me how driving on the freeway knocks the range down!
I have a feeling that my heater may not get as hot as the one running on diesel. I'll also have to try running the heater on straight gasoline and see how it compares for heat and fuel consumption.
Of course, the clerk at the gas station is going to look at me funny when I buy one liter of gas!