Function and Appearance
Electric cars, as implied by the name, most likely used electricity as an alternative to gasoline, which polluted the atmosphere.
All of the cars were a metallic light blue color. They had no doors or windows but instead, open space on the sides. In fact, the only cover was a roof held up by four thin rods. The cars had two seats only, one of which was the drivers seat. A small basket for carrying objects was located behind them. They had four wheels, a very small hood and no headlights. The cars either drove quite slowly or nobody cared to drive them very fast.
Citizen Brown's Car
The electric car used by First Citizen Brown differed from the others. It was dark silver with gold lining. Its license plate was gold colored and had a single word -- "BROWN". Unlike others, this car had windows, which were opaque to anyone standing outside. Because of the windows, the number of seats in the car is unknown. It was longer than most electric cars and was known to have back seats, however, as that was where Citizen Brown and one who had an appointment with him sat.
Electric cars were used extensively and seemed to be the only method of transportation aside from walking. Apart from Citizen Brown's car, every one of them appeared to be the same model and color, even those used by the Bureau of Discipline.
When Marty first arrived in the alternate 1986, he walked right in front of a moving car while observings his surroundings, forcing the driver to stop short. This was an action that he had been known to unwittingly do several times in various timelines.