First of all there is nothing "modern" about a mechanical gauge. An electric gauge would be more modern. Send pic of gauge face after it settles while driving. Or provide part number. It's all about perception, hash marks and thermostats....and you are in New England and we don't know the temperature (30-60) or how much antifreeze you put in.
You are seeing that it reaches 180 then cools off with forward motion. That's what it's supposed to do.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn