Let's try to revive this with an easy one:
1. The car was designed and built for a big manufacturer by a small firm.
2. They were regularly transported in Boeing 747s.
3. It became sadly known as "all show no go" car.
I can think of other 2 but I don't think they meet all the clues:
Subaru SVX - design signature and multi million $ loss but doubt about the other two.
Isuzu Piazza
Clues
1. Its designer produced some of the most stunning sportscars in the world.
2. Its engine is known for its reliability.
3. At the end of its life it was produced for a single country.