Dear Car Talk:

When I owned a 1964 Chevrolet Impala convertible, I designed and installed a rain-detection system so the convertible top would close automatically when it started to rain. This system never failed me in the six years I owned the car, and I would purposely leave the top down even if it was expected to rain -- just so I and others could see it go up.

With much better technology now, why is this feature not available on convertibles today? -- George



Good question, George. It's certainly technically feasible. The skylights in my house do that, so why not a convertible?

I can think of a couple of reasons why manufacturers might not want to add a feature like that. One is that today's convertible tops are so easy and quick to put up and down, there's very little incentive to leave the top down when you park the car. It literally takes 10-15 seconds, and no effort other than pressing a button to close up the car completely -- including securing the top and closing all the windows.

So why would you leave your car exposed to the sun, debris, bums who want to take a nap, and the guy who doesn't know where else to throw the wrapper from his lamb gyro? It's so easy now, you can put the top down for a three-minute drive to the convenience store on a nice day and put it back up again, and not feel burdened.

The other reason I can think of is that the manufacturers might not want the liability. Even though the technology is good, what if it fails? Do you think Jaguar wants to pony up for an entirely new Freedonian leather interior because a five-dollar moisture sensor failed? Or because you parked under a low tree limb that blocked the top from closing?

But maybe some of our readers in the automotive business have a more conclusive answer for George. If you know why this feature hasn't been offered yet, write to us via cartalk.com.