Brumation / Hibernation

I guess this is as good a place as any for this discussion.
First let me ask for leniency if this topic is old or settled. Forgive my ignorance.
Typically we assume reptile "hibernation" is an attempt to stay warm during inhospitable weather. And to a degree that would be true especially in truly lethal conditions. But are all reptiles seeking the HIGHEST temperature available? In many other animals, (notably Bats) hibernation means finding the COLDEST tolerable temperature. Hibernation is not just avoiding dangerous cold, but also serves as away to conserve energy whey food resources may be limited or completely unavailable. Low body temperature equals low metabolic cost. It would seem to only make good biological sense to spend the winter as COLD as possible without freezing rather than seek out the WARMEST refuges available and burn energy when it least obtainable.
I am not suggesting that keepers of reptiles buy refrigerators for their herps. It has obviously been demonstrated that most reptiles do not REQUIRE massive cooldowns. But this is an artificial environment and animals may respond artificially to certain conditions.
I am just curious if anyone has explored how wild reptiles actually respond to the onset of inclement weather.