Premature leaf fall would thus be a bad thing.

ECONOMIST: The science of autumn

Under an expanded New Electric Vehicle Limited Warranty, Nissan will protect against capacity loss in LEAF batteries that fall below nine bars, of the available 12 bars displayed on the vehicle's battery capacity gauge, for the first five years or 60, 000 miles in the United States, whichever comes first.

ENGADGET: Nissan upgrades US Leaf warranties, will 'restore' batteries that lose too much charge

Both natural events bring the Japanese out en masse to celebrate the changing seasons, with hanami (cherry blossom viewing) parties in the springtime and momiji-gari (maple leaf viewing) in the fall.

BBC: K��y��: Japan��s autumn explosion of colour

For inspiration, McCann staffers could scrounge up, for example, a link to a recent long-form video produced for Nissan last fall as a promotion for Leaf.

FORBES: Memo To McCann, Mahoney: Come Up With Better Volt Ads

So, on this bit of tea-leaf reading, we're off to the races so long as shares don't fall more than that 2.5% today.

BBC: Will 2013 be a bull year for shares?