Here I deal with a case that's not design theft, but it comes fairly close to it. For 1993, Chrysler finally abandoned its K-car bodies for the new LH platform. The initial Chrysler brand car using LH was called the Concorde. Its passenger compartment greenhouse was conventional for its time. The following model year, Chrysler added top-of-the-line models using the New Yorker series name that had been around since 1940 along with a nearly identical LHS model.
To distinguish the New Yorker and LHS from lesser Chryslers, they were given a different roof treatment. This created some controversy (among car buffs, at least) because the aft part of the roof was similar to that used by 1950s-vintage Jaguars.
The design looked nice and did give the New Yorker and LHS a measure of distinction. On the other hand, the same result could have been attained using a different theme.
This was the base model Chrysler design first offered for the 1993 model year.
And here is the New Yorker variation. The grille ensemble is different as is the trunk and rear of the greenhouse.
Profile view showing how the aft of the top tucks down towards the trunk.
Rear three-quarter view. Note the following: the tuck-down curve; the backlight / rear window position; the curved shape of aft side window. Compare these to the Jaguar below.
True, the details just mentioned are not identical. After all, the Jaguar predated the New Yorker by 40 years and automobiles in general had evolved. Yet the cars share similar aft side window curves, greenhouse tuck-down, and the setting (if not quite the shape) of the backlight.