Ah, good point. Moderately cold (by California standards!) and dry is best for just using the heated seats. If you've got fogging, that definitely has priority. But still, you can save a bit on energy if you don't have to heat the entire cabin quite as much. With my Roadster, which is rather drafty under the best of circumstances, trying to heat the cabin can be futile. The Model 3 should be much better from that perspective, but then the cabin is also a teensy bit larger.Normally that's not how it works. If it's worthy of turning on the seat then you'll need to run at least some cabin heat to keep the fog off the windshield.