Another excellent article by bio-d at Grist on possible ways to convert a Toyota Yaris to a partial plugin hybrid. This idea may fit your vehicle with a fairly simple kit of parts and easy installation by a local mechanic or do-it-your-selfer.
This is interesting bio-d, use only a couple of extra plugin bateries (cheap heavy ones would be ok) to boost your mileage maybe 20 mpg? By only having the extra plugin batteries power the electric part of the car, including restart (that eliminates the 30 second payback rule) and move it at low speed without restart.
Why use gasoline to recharge the starting battery or power any accesories? use grid power in the extra batteries. Put the alternator on the "off" position even when your engine is running too, because the extra batteries would tell the charge circuit the battery doesn't need charging, no switches needed.
Depending on how much time one spends stuck in traffic creeping at under 10 mph, this could get you 20 more miles per gallon. A compression release for the gas engine would be good too (not sure how difficult that would be), and maybe an electric oil pump to maintain oil bearing pressure in the engine when you creep forward at low speed on electric power through the starter.
Also realize that much more powerful 24 volt starters are available after market. They are used to crank high compression hot rodded engines. Some sort of cooling for the starter might be good, fan forced or liquid heat pipe. That'as a pumpless liquid cooling system, it pumps the fluid with the waste heat to a radiator.
You won't need a trailer this way. If you could get even 20 mpg more with a few extra batteries, an electric oil pump, and an aftermarket starter added to your engine switch, that would be a coup!
Go for the easy cheap, low hanging plugin fruit, so to speak. Sure plugins will go 60 miles at full speed on a charge someday, but the batteries to do it are held closely by corporations now and far too expensive.
Great sequel to your bike. We're right behind you, go for it!
