On 2011-05-25, a wrote:
What is really interesting is that high performance glider wings are
long and slender: that's how they get the most efficient use of
potential energy in the form of altitude and turn it into range. I
don't know of any 4 seat complex SEL that uses the same principle and
am not sure why. My Mooney gets 20 mpg or so, sure would enjoy seeing
that change to 30!

The reason why is that you have tradeoffs - long and slender wings
won't work so well for a much heavier plane (more heavy structure) that has
to go much faster (more form drag). Even performance gliders are slow
compared to, say, a Beech Bonanza (I got all excited about flying
a Discus, now I could transit across areas of sink at a whopping 90
knots or so).

Some 4 seat planes have longer, higher aspect ratio wings than was
traditional, for instance the Diamond DA-40 which has trouble fitting
in a lot of T-hangars due to its wingspan of 40-odd feet. However I suspect
much beyond that wingspan you're going to start losing more than you
gain in parasitic drag and extra structural weight to have a very
long, slender wing in a 4 seat plane that goes more than 140 knots in
cruise.