I have to say, im excited! for a purpose built vehicle like mine, I can get the acceleration using what electric motors are great at (takeoff torque) and range using what ICE's are good at, particularly diesels (droning on for hours on end right smack dab in the middle of their efficiency curve)
and wind up with something nice, possibly even in the 200mpg range.
Using the EcoModder tool, feeding in all the "knowns" and making educated guesses at the rest, it puts the 70mph requirement for my vehicle at about 3500 watts.
Take a 10hp diesel with a 200 gram per kw per hour (got the info here:
NEW 10HP Diesel Engine Electric Start Tractor 10 HP - eBay (item 180588653876 end time Dec-16-10 16:21:41 PST) )
using 5.5hp (fudge factor) thats 200 grams x 5 = 1000 grams. there are 3213 grams in a gallon of diesel so 3.2 hours of running time to the gallon.
3.2 x 70 = 224 miles to the gallon
but...
going serial hybrid and using the electic motor as the drive engine, (and using high efficiency and not too expensive etek style motors) your losing say 10% at the gen and 12% at the pack, controller, and drive motor
so 10hp - 10% = 9hp 9hp- 12%= 7.92 so your losing 20.8% to the serial system.
Brings you down to *Only* 177mpg at 70mph
I could live with that, not to mention the 40 or 50 miles of electric only driving youd get from a wall charge)
The thing that I dig is using the next best thing, a transmission equipped motorcycle engine to drive the trike (without an e-motor as the primary motor, you'd need that tranny) your burning 354 grams per kw per hour. damn near twice the fuel...
Makes the 20.8% losses to the serial drive train not look so bad :-)