The Vespa 400 is a rear-engined microcar, produced by ACMA (Ateliers de Constructions de Motos et Accessoires) in Fourchambault, France, from 1958 to 1961 to the designs of the Italian Piaggio company. Two different versions were sold, "Lusso" and "Turismo".
The car is basically a two seater with room behind the seats to accommodate two small children on an optional cushion or luggage. The front seats are simple tubular metal frames with cloth upholstery on elastic "springs" and between the seats is the handbrake, starter and choke. The gear change is centrally floor mounted. The rear hinged doors have, on the inside, only a plastic lining on the metal skin allowing for valuable extra internal space. Instrumentation is very basic with only a speedometer and warning lights for low fuel, main beam, dynamo charging and indicators. The cabriolet fabric roof can be rolled back from the windscreen header rail to the top of the rear engine cover leaving conventional metal sides above the doors. The 12 volt battery is located at the front of the car on a shelf that can be slid out and the spare wheel is in a well under the passenger seat.
The British Motor magazine tested a 400 de luxe saloon in 1959 recording a top speed of and acceleration from 0- in 23.0 seconds and a fuel consumption of . The test car cost 351,725 French Francs.