I came across a post yesterday that led me to believe it was in the law - should have known not to assume it was true without verifying. The law text has no mention of base vs option MSRP as I just read it. What I had seen yesterday was an excerpt from Ford's disclaimer section saying base vs...
That's debatable, will just have to see what the IRS officially says. The ER pack is included in an "option" and per the wording in the law, options are not used as part of the MSRP calculation. The Lariat base trim MSRP is ~$75K and would qualify as either SR or with the ER option.
You are way underestimating the power required to use resistive heat to warm freezing outside air in a poorly insulated cabin with cold, high winds (when driving) flowing over the body. It is significant. You will constantly draw 3-5 kW in freezing temperatures to keep the cabin around a normal...