It's all pretty absurd, but I can't claim to know a better way of getting around that touchy Batman subject. And if you do make contact with an enemy while in the Batmobile, the car delivers an electric shock to your victim, followed by a hilarious grunt or moan - which is basically the game's way of saying 'Batman didn't kill that guy, he's just electrocuted and knocked out, but he's still very much alive, we promise.' During car chases you can fire homing missiles that will explode and flip the car you're chasing, but the bad guys always seem to crawl out of the wreck unscathed. When it's aimed at bad guys, the Batmobile fires non-lethal rubber bullets.
So obviously being the Batman purist I am, I immediately began to wonder, 'how the hell is Batman not murdering people left and right with this thing?' Well, it's complicated and requires a bit of suspending one's disbelief.