Just finished installing the diesel heater on my EV. It appears to work rather nicelly even without the extra mass of the engine block. The complete system has about 1.5l of coolant on the hoses/heater/burner and an additional half liter on the expansion tank, which is just sitting there (not heated).
With an outside temperature of 5C the unit takes about 5minutes to go into part load (5 to 2kW) with the blower on Max. At lother fan speeds it just cycles on/off as needed. So overall, I'm quite pleased with the system. True hot air for the first time in 3 years
Rated fuel consumption is 300ml/hour at full speed. During my tests the unit used about 200ml for a whole hour as it cycled on/off.