The BEST car shovel for all around duties that I've found, bar none, is a standard garden shovel with the handle cut down so it is about two feet long including the blade. I've dug my car out a few times with it, and while it might not work as well as snow shovel with powder, it works better on anything crusted over with ice, or piled up by the snow plow in big chunks.

And it's cheap, to. Like $15 for a good shovel at Home Despot, a minute with the saw in a Leatherman or SAK, and you are all set before you even leave thier parking lot. And what you take off makes a good thumping stick.