Modern batteries may have improved that to a two liter gas tank and
half a ton of lead, but it's still hard to get the energy density you
find in oil products.

True that, but with efficiency ratings in the neighborhood of 18-22%
common for IC engines compared to 85-98% common for electric motors
(not to mention the flat torque polar...), the difference is not quite
as drastic as dry energy density numbers elude to...

One could use a suitable reynolds number prop for the average altitude
of operation. A sea level prop, a half mile prop and a mile prop ought
to cover 90% of operations in the world.

With electric motors in the wheels (much more efficient for getting up
to flying speed than a prop, especially tugging dead weight...) and
regen braking, one wouldn't need as many battery packs sitting on the
charger. Maybe not today... maybe not tomorrow... but maybe someday.

Oil can't be generated, electricity can.

-P