The SMZ was a Soviet cyclecar or microcar, manufactured in Serpukhov, Russia, by Serpukhov Motor Works (, Serpukhovskiy Motozavod), later known as the now-defunct SeAZ. The most common models were the S-3A and S-3D. They were specially designed for disabled drivers and were distributed in the USSR for free or at a large discount through the Soviet Union's social welfare system, and were not officially sold to non-disabled people.[1] The S-3A-M was produced between 1958 and 1970. It was powered by a 346 cc single-cylinder two-stroke engine, giving 10 hp and a top speed of 55 km/h.
The S-3D, produced between 1970 and 1997, was a twin-seat, four-wheeled cyclecar, 2.825 m in length, but rather heavy (≈500 kg) due to its all-steel body. It was powered by an 18 hp IZH-P3 air-cooled two-stroke engine.
In the USSR, the model was commonly known as a "motor-wheelchair" (, invalidka) because they were only leased via the social care system to disabled people for five years without permission to sell (in a similar way to the British Invacars, made by AC, Thundersley and Tippen). After five years of use, a lessee had to return his "motor-wheelchair" to the social care organisations and was given a new one.
Like the Invacars, not all invalidkas were scrapped, because some of their disabled lessees managed to register them as their private property. However, nowadays [when?] they are rare, and earlier models are exceptionally rare and have become collector's items.