In March 1949 an upgraded model was introduced called the EMS-49-II. This new version had an enlarged battery pack with 250 amp hour of output, which increased its range to a full 200km, and upped the top speed to 55kph. The extra battery capacity however added another 126kg to its total weight, bringing it now up to 1776kg. Previously hard to get materials such as chrome were now starting to become more readilly available again in post-war Japan, and the new model featured lashing of chrome along it sides and an ornate grille to demonstrate its place as a higher price point vehicle. A 4 door version was also added to the range at this time, which pushed the weight up to a staggering 1930kg.

A final version was released in February 1950 called the EMS-49-III. This featured a new grille with a chrome surround and a single horizontal bar in the middle. The coupe variant was dropped from the range, leaving only the 4 door.

Production of the Tama Senior continued until early 1952. By that time political upheaval in a foreign country would set off a chain of events that would kill off the Japanese electric car industry. In 1950 the Korean War erupted, and although Japan was not directly involved in the conflict, it would feel the effects. The Korean War triggered a global supply problem for lead, which is a major element used in lead battery production. Between 1950 and the end of 1951 the price of lead in Japan had increased tenfold, and suddenly the electric car was no longer economically viable. Luckilly, at around the same time the rationing of petrol had reduced considerably, making petrol engined cars much more viable. The Tama Senior and Junior would be the last full electric vehicles in Nissan's history until the Nissan Leaf arrived in 2010.