I'm a registered nurse and I have a question that is somewhat medical in origin. The appendix is an organ that is believed to have once had a function but is now without purpose (except as an income generator for the surgeon who removes it). And yet, there it is - a stubborn piece of our anatomy, refusing to succumb to the laws of evolution. Is there a part in a car that has not evolved over time but continues to exist even though we don't need it anymore? -Linda

Tom: Great question, Linda! The "part" that comes to mind is the parking lights.

Ray: Right. In the old, old days, when my brother still had a few brain cells left, cars were not that common. So when you parked yours at the side of the road, you left your "parking lights" on. That way, when Ichabod Crane came whizzing by in his buggy, he wouldn't smash into you.

Tom: But now that we all expect cars to be parked on every street, and we have reflectors to make them more visible, parking lights are hardly necessary.

Ray: And if it's dark enough to turn on your parking lights, why not turn on all of the lights? It's safer, anyway. So that's the car's appendix.

Tom: There's also one other part that was starting to go the way of the parking lights but has recently had a reprieve: the cigarette lighter.

Ray: Apparently, fewer people are smokers these days, and many people decided they didn't want cigarette lighters in their cars.

Tom: So the manufacturers figured out that by slapping a plastic cover on the cigarette-lighter socket, they could save the cost of the lighter itself and brag about their "power ports." So that's a part whose function has changed and evolved with time.