Owen F sends us the Saab Monstret (Monster) - a one-off experimental prototype built by Saab in 1959 by joining two separate three-cylinder, two-stroke engines into a modified Saab 93.    Engineers mounted the two transverse 748cc two-stroke, three-cylinder engines side-by-side under a lightweight plastic hood, creating a split inline configuration that drove the front wheels.  The combined 1.5-liter setup pumped out about 138 horsepower - achieving a top speed of 122 mph)during testing at the Såtenäs airfield. The extreme front-end weight caused severe understeer, and the aerodynamic teardrop shape of the 93 made the rear end dangerously light and prone to lifting at high speed.  The project was ultimately shelved because motorsport regulation bodies refused to let such an unorthodox configuration compete.
More pics and information here.