My vehicle clock altered itself

Are you really sure you didn't just neglect to change it at the previous switch?

take the batteries out for an hour ...

On digital clocks this will only work if you put the batteries back in at midnight or noon, since that's the time nearly all of them "reboot" to. And then you've still got to figure out how to stop the #!$@# thing from blinking at you.

And some "plug-in" digital clocks (especially alarm clocks) have an internal battery that keeps the same time for more than an hour with the power off, so you'd probably need a day or two unpowered to run down the battery, and the same "plug in at noon" procedure.

Many "battery operated" analog clocks only use the battery to wind the spring, so you'll have to figure out how long it runs without being re-wound and add that to your hour of "off time." (It was about 18 minutes on the one I checked last year; but they appear to have a wide range of variation.)

John