The first postwar Mercury was introduced in the 1949 model year. The engine was a flathead V8 that produced slightly more power than the then also newly designed 1949 Ford. A new overdrive system was optional, activated by a handle under the dash. The styling of the Mercury Eight, when it was released in 1949, adopted the "ponton" appearance, and was successful in both ending the monotony of warmed-over pre-war style, and differentiating Mercury from its comparable Ford cousin, a trick that spelled sales success. Sales figures for both Ford and Mercury broke records in 1949. The new approach to styling was also evident on the completely redesigned Lincoln and the all-new Lincoln Cosmopolitan. The Mercury Eight used full instrumentation. An 8 tube AM radio was available as an option. The 4-door station wagon was replaced with a 2-door model. Although the wagon now featured an all-metal roof, its sides still consisted of wood panels, manufactured at the Ford Iron Mountain Plant.
Within its era and beyond, the Mercury Eight was popular with customizers. In 1949, Sam Barris built the first lead sled from a 1949 Mercury Eight; the Eight became the definitive "lead sled", much as the Ford V-8 (as the "deuce") was becoming the definitive hot rod. The Eights were among the first models to receive an aftermarket OHV engine swap, since Oldsmobile and Cadillac developed the first high-compression OHV V8 engines in 1949, whereas Ford was still using a sidevalve engine. Sam and George Barris also used the 1949 body style to build "the most famous custom car ever", the Hirohata Merc, for customer Bob Hirohata in 1953. Setting a style and an attitude, it had a "momentous effect" on custom car builders, appeared in several magazines at the time, and reappeared numerous times since, earning an honorable mention on Rod & Custom's "Twenty Best of All Time" list in 1991. The Eight remains a very popular subject for car modellers.
Fiberglass replicas of the Eight, inspired by Sam Barris's car, are still in production and are popular with custom and rod enthusiasts