BAT5 was the first of the Bertone-Alfa Romeo BAT project. It was first shown at the Turin Auto show in 1953. The design of the model was based on a study of aerodynamics. The shape of the front in fact aims to eliminate the problem of airflow disruption at high speeds. The design also aims to do away with any extra resistance generated by the wheels turning, as well as achieving a structure which would create the fewest possible air vortices.

In practice these rigorous criteria would allow the car to reach 200 km/h with the 100 hp engine mounted as standard. The design that Bertone came up with was for an extremely light car (1100 kg), the ultimate in streamlining, with side windows at a 45 degree angle respect to the body of the car and a large windscreen which blends in perfectly with the almost flat roof. The most surprising part of the car has to be the tail, with the length-ways rear windscreen divided by a slim pillar, and the two fins tapering upwards and slightly inwards, for a highly aesthetic finish.