Sure there's a way to keep the car from using its own battery, if it's phoning home regularly via the cellular network. If you don't pay the battery bill, they shut it off by remote control. It's kind of like computer programs that phone home every time you use them, and stop working if you don't pay the support bill.
Thing is, with programs like that, you give up privacy and ownership rights because you REALLY want or need the program. Exactly what is this car offering that you can't get in some other car that doesn't keep its nose up in your business all the time?
Funny thing though - some folks just won't put up with that. That's why some people root and jailbreak their mobile phones, why some buy region-free DVD players.
Never underestimate the power of entrepreneurship. If this car catches on, I predict that someone will offer for sale a battery crack that lets you use the bricked battery that's in the car, and/or lets you replace it with a generic Chinese Lithium Iron Phosphate battery - which you'll also be able to buy on eBay. It will also neuter the car's ability to phone home - or, better yet, direct it to send bogus data back to the spooks.