I don't think that correlation is due to the cost of gas & Tesla's demographic of car buyers (the wealthy). They are are not as sensitive to changes in the oil price (ie. they at 3 vs. 4 @ the pump, a given wealthy person will consume the same).
You also know that Tesla has a waitlist for purchased cars, so changing gas prices do not impact immediate sales in any case.
Thus, why the relationship exists is an interesting question -- I think it's because investors assume the relationship exists, and then react strongly to market news, thus strengthening the assumed relationship. Maybe this is a good example of a feedback loop.
