This is a Batmobile of my own design, taking cues from the Keaton Batmobile. My design features an opening cockpit (space for two minifigs), road spikes (which work when two panels at the back are flipped up; spikes rest on slopes, and gravity does the rest), and the front cowling of the Batmobile splits in two, and folds to either side, revealing twin laser cannons. Also, air brakes beside the cockpit can deploy.
Awesome batmoblie! I'm on my fifth to, I think that the whole point to building your own batmobile is to make it with all the secret functions you like/want(I love the folding laser guns by the way). I think that you might like these others for more inspiration and more gadget ideas-
http://www.mocpages.com/moc.php/158878http://www.mocpages.com/moc.php/395976 (the second one is mine and the other is one of my favorites)