This Swedish inline-four debuted in 1981, but it was essentially a redesign of the 1972 Saab-Scania B engine, which itself was based on the- wait, can this be right?- Triumph Slant Four engine.
The H is still being manufactured to this day, serving in the Saab 9-3 and 9-5. That means that the engines that power those two vehicles are not-too-distant relatives of the wonderfully horrible Triumph V8 in the Stag! By the time Saab got around to the H, however, the reliability had been improved by several orders of magnitude over the Triumph four, and nearly 30 (or 40, if you count the B engine) years of front-line service stands as a very impressive engineering achievement. We don't recommend the H as a 24 Hours Of LeMons engine (though the Box Wrench Garage Saab 900 Turbo managed to finish fourth at the Goin' For Broken '09 and fifth at the Altamont '08 race), because of that rod-throwing thing, but it makes for a solid street engine with plenty of turbocharged power potential.