Sometimes it's still quite shocking to me when I notice older generations of full-size trucks are smaller than a modern mid-size (which Americans may still be used to classify as a compact). This 43y.o. F-100 may not look or feel oversized compared to a brand-new Ranger for instance...
A seemingly desperate attempt to improve fuel-efficiency was the fitment of smaller engines into large vehicles, in a time when people tended to see the amount of cylinders as inherently tied to fuel-efficiency. For instance, in Brazil Ford went as far as offering the 4-cyl 2.3L OHC Lima engine to a local version of the F-100.