Would it help to put something like a heating pad or hot water bottle on the batteries at night or in the hours before you plan to drive your electric car?
Well, the hot water bottle is an interesting comment. In my situation, that would be a "freezer pack" by morning...but the other idea isn't so far fetched.
Kat's, the same people that make engine block heaters,also offer a battery heater. It's like a heating pad that wraps around your battery. Now the battery thinks it's Summer time when you go to start.
Of course, that's just for a single car battery. But you might be able to construct something out of heat tape or roof-edge heating cable.
You'd want to be damned careful though, and test it on some milk jugs full of water, or cement blocks first. No need to give that electrocar another reason to go up in flames.