The best auto escape tool I've seen so far was the Benchmade 10105 ERT-1 that was reviewed by Doug at SHOT Show 2007. It seems that it is one of the most versatile automobile escape tools made, including an LED light (that is conveniently aimed at the cutting blade), a spring-loaded window punch (which many believe to be superior to manual pointy-metal punches), and a folding/locking safety blade.

The only question I have is how to best store one of these (or any rescue tool like it) in your vehicle so you're sure you can reach it in an accident. The ERT-1 comes with a pocket clip, which is fine if you put it in your pocket, but I'd be afraid of it flying around in your car if clipped anywhere in your car. (Even a 3.6-ounce knife would hurt like hell when moving at 60 mph.) It also comes with a nylon sheath that can be mounted somewhere in your vehicle, and as long as the sheath is securely mounted, the knife should remain secure in the sheath until the moment you need it.

There's also always the option of sticking the ERT-1 in the glove box or center console compartments, but I prefer to avoid those locations for fear of the compartment being jammed shut or inaccessible after a collision.