Well here is a little update on my experience with the diesel heater (dh) in the imiev. I'll give more of a qualitative evaluation rather then look at the numbers. Maybe I will post some canion numbers a little later on.
By the way, Anyone with canion can see how much they are spending on heat. Its pretty easy to convert those heat WH into miles or kms. You could decide if a fuel heater is worth it for you.
First of all the heater is either a fantastic range extender or a useless 4 kg weight in the car it depends on your use of heat in an ev.
If your one of those people who can drive with no heat and it doesn't really bother you then the heater is useless and does not extend range. This may be obvious but its worth mentioning because there are people who are content to drive with no heat in the ev for whatever reasons.
If you drive your ev with "survival" amounts of heat only to defrost windows for example then the dh starts to make a little sense.
If you drive using as much heat as you can for comfort but still making it to you destination then the heater becomes a good range extender.
If you like your car warm and you need or want as much range as possible for peace of mind or you just need it to make you destination then the heater is indispensable.
Basically the desire for comfort in the car for the driver and passengers is the real driver for this kind of extra heater.
Once you have it You definitely get used to having the heat and soon become dependant on it and then you wonder how you ever did without it.....
In very cold temps of < -20 deg c the heater really pulls its weight and you see the greatest range increase and greatest comfort increase.
The dh also give you have a lot more confidence that you can make your destination. You can basically do more with the car in these bitter temps Without getting frostbite....
It is pretty much a linear relationship of temp vs range extension up to about say + 5 deg c where you don't really need the dh the electric heat is fine unless you are really pushing the limits of the car's range. At + 5 deg C its much easier to run the car with no heat and have the same result dh installed or not. Actually when the temps are up i just use the stock heater most of the time. I also use the stock electric heater in very cold temps when I am just doing a very short drive.
I don't have any numbers but the fuel heater is hotter then the electric one. Its kind of like the turbo button on the old pc's. But it is slower to get going. It takes 4-5 minutes to get heat when its really cold. The stock heat is more like 1 minute to warm up.
So overall for my neck of the woods it's a great idea.
Two things are problematic in my implementation:
My 1.8 liter fuel tank needs to be filled a lot when it gets really cold. More then I thought I would need to fill it. Like i said you get used to the heat. I should figure out a larger tank, 10 liters with a gauge would be nice.
Second with the heater in the front of the car in stop and go traffic and with the fan on max some of the exhaust seems to get sucked into the car not much but you can detect it. Its fine as long as the car is rolling but at a stop light I have to lower the fan to half or less. I need to run the exhaust more to the side and away from the car. That will be my next project when it gets a little warmer.
Also on the down side you do need to fiddle with starting the heater and setting a runtime and then setting the normal heat controls to heat for a second to direct air thru the heating core and then back to the green dot to stop using electric heat. Not really a problem for me but still a few manual things to keep track of. The whole system is not very automatic at all. Not aproblem for me but for some a completely automatic system with the dh kicking in when it gets really cold or the battery is at 50 %would probably be nice for some people.
Another thing, The heater does make noise. In the cabin when your rolling with music on low you can hear the fuel pump and the exhaust blower but its not loud enough to bother you.
Outside of the car you hear it much more its like and enhanced AVAS (did i get that right ) maybe a great safety feature in the winter. Some people may not like the extra noise but to tell the truth at -20 deg c all the windows are closed and you could care less about sound. Your completely isolated from the outside when your in the car.
For me its been a progression of one winter with only L1 charging to a second winter with L2 to a third with a diesel heater. Each winter so much easier then the previous one in terms of heat and comfort in the car.
Of course my wife and kids are much happier in the car in the winter with the heater. The imiev is no longer known as the car you freeze in.
So of course its no surprise that I would recommend this mod to anyone who experiences these really low temps and would prefer to be in a warm ev rather then a freezing one. I guess if it was a factory option then everyone in the north would take it. I think the first winter is a little bit of a rude awakening for new ev buyers. A dh option on the car could eliminate that.
Now that being said if you have no need to ever do more then 50 km in the winter then the stock heater is fine. Its clean, easy to use and never needs to be filled up.