sentences:  The vehicle was originally prototyped starting in 1946, making it the first all-new Jeep to be designed for the U.S. military after World War II, and further developed during the 1950s by a team including four of the original Bantam engineers.A design called MARCO MM-100 by the Mid-American Research Corporation used a Porsche air-cooled engine and independent suspension.A unique feature was the absence of a conventional exhaust system.