Replacement of engine (swap engine) is not an unusual thing, we remember SAAB powered Opel Vectras. The idea of engine swaps has been around longer than you think, but cross-pollenating dissimilar powerplants and chassis with one another is a phenomenon still relatively new.
An Swapper and car enthusiasts, used the Saab B206 engine and threw it into the BMW M3 (E30). His motivation for this engine swap: Wish to have more horsepower and torque, without having to rev that high. So, a stronger engine than the ‘original’ 265 BHP S14 engine and still reliable and relatively affordable. No discussion, the BMW S14 is a truely magnificent revving engine with a ‘goose bumps’ sound. But they are relatively expensive BHP’s and not as many as from a little modified Saab B2**-engine.
Saab engines in older BMW cars are no longer a novelty (Saab-BMW swap 2009), and below you can see one of the latest Saab-BMW Swappers: