According to Fifth Gear, the owner of this monstrous 1981 Rover SD1 was looking for a project that he could work on for a long time, and that would be a challenge.
Fitting a 27-liter V-12 to British-Leyland's most extroverted sedan certainly has no shortage of challenges.
The engine produces around 650 horsepower and 1,550 pound-feet of torque, and originally drove a tank. It's derived from the legendary Rolls-Royce Merlin engine that powered the P-51 Mustang and Supermarine Spitfire World War II fighter planes.
While the engine itself was basically scrap, its operation is still a matter of British national security. The owner's manual had to be illegally photocopied. Once he knew how the V-12 worked the owner basically shaped the entire car around it.
The result is a home-built supercar with surprising performance. The SD1 topped 160 mph while the engine was turning at just over 2,000 rpm. No shrieking 9,000-rpm antics here.
This build is probably the best marriage of automotive and airplane components short of a car actually built by an aircraft manufacturer, and it shows that the classic formula of small car, big engine (or in this case big car, bigger engine) still works regardless of what variables are involved.