chris asked,
"why did audi pull the 5cyl TD out of the US market
in '83 if it was such a good car??"

Americans were disposed toward buying the most
fuel efficient motors while the fuel crisis was fresh in
their minds.  When it became a memory, the market
for diesel cars and light pickups virtually disappeared.
It takes a fairly high sales volume threshold before
an automotive organization can make a profit by
selling those models.  Take a stunningly reliable design
like the Mazda diesel they fit into pickups.  It even
eliminated any need to service timing belts or chains
by going to a 100% gear drive system like a true
industrial motor.  They didn't stop there.  They ran
TWO oil filters, a full flow filter and a separate bypass
filter.  These are features normally found on very
expensive equipment, not a modestly priced pickup.
These motors can easily go half a million miles
without needing a rebuild if you run synthetic oil.
Even they dropped out of the US market after 1983.
The reason was partly the lack of fuel price pressure
and partly due to the genius shown by GM in
producing their infamous 5.7 liter series of diesels
which often didn't make it to 35,000 miles without
self destructing.  While voting citizens were born
after this motor was dumped on the American
market, some silly people still cite it as evidence
that diesels are, in general, undesirable.  It's virtually
all an American phenomenon.  In England for an
example, approximately 25% of all new cars are
sold with new clean burning diesels.  Go test drive
a VW TDI diesel to get an idea of what's fairly
current.  But understand that the newest VW TDIs
being released in europe have FAR more torque
at low rpm than even these amazing TDIs which you
can drive here.  The new unit injection system adds
21% more peak torque, which is close to the
difference between a 4 cylinder and a 5 cylinder!
They now will out accelerate any equally hp.
rated production gas motor as well as get much
better fuel economy.  Things have changed.  It
will take a while for this information to filter
down to the American market, but eventually,
"truth will out."
John