Hello all,
So the topic, if I understand it correctly, is to have a battery-biased hybrid vehicle, where the ICE is sized only just large enough to push the vehicle down the freeway at peak BSFC, and is hopefully removeable completely ("modular hybrid") for the much larger quantity of miles that are to be driven well within battery range.
Obviously, any hybrid is going to be a compromise, in that you'll be carrying extra weight/complexity around, and thus not be as efficient as an optimized EV-only or ICE-only vehicle. Driver ability, weather, usage patterns and location will influence the point at which either of those two poles do or don't make sense - and that point will also vary based on what metric(s) is(are) being considered. Best miles per ton of CO2 emitted vs. best miles per dollar vs. best miles per gallon of oil pumped, vs. best number of dollars per year, etc. Diesel manual pure ICE may emit the absolute least amount of CO2 per year, but not everyone can drive perfectly do do that and at some point the trips are too short for a given weather region to get good longevity out of the engine without preheat. Heated garages, shore-power block heaters/cabin pre-heaters, etc. use power and at some point charging an EV or plugin hybrid instead starts to beat it.
Starting at the EV-only end of the spectrum, at what point in "don't drive outside of battery range most of the time" does it make the most sense to borrow/rent/hire an efficient ICE car for those few out-of-range drives, and then at what point does having only a plugin hybrid like a Volt or Prius make more sense? I'm leaving out non-plugin hybrids and pure ICE vehicles as being out-of-scope. Somewhere on this spectrum is where the "modular hybrid" comes in. I'm just not sure where, except for hobbyist/enthusiasts that want to do something neat/different - which is of course a completely valid reason to do it.
For a "modular hybrid", the "Pusher" architecture neatly sidesteps a lot of system integration hassles. An ICE Pusher can charge the host EV "through the road" - the EV just "feels like it is going downhill all the time". Angel And The Wolf's idea of connecting the engine to a retrofitted rear differential is probably lighter than a standard Pusher, at the expense of more fabrication and more "unneeded weight" when not lugging the engine around. I would imagine a weight-distributing hitch would do the job of getting sufficient traction on Pusher drivewheels if going the usual way.
If the dismountable engine is being mounted directly to the EV to drive a pre-integrated driveline, major bonus points for making it look like an outboard motor off a boat instead of a funny-looking generator on a cargo rack. Some Honda outboards use the same engine block as a Honda Fit, btw...
