Not long after the introduction of the E4S-48 Shojiro Ishibashi, the head of the Bridgestone group, decided to make an investment in the fledgling company. Thanks to his investment they were able to purchase the old Shoda aircraft factory in Mitaka, which saw its production capacity to increase to 70 vehicles a month.

The investment also allowed some major improvements to be made to the car, and in July 1949 the updated E4S-49-1 model was introduced. This now had an all steel body instead of the previous timber framed design. The motor was changed from 35 volt to 44 volt, and the battery pack was upgraded to 44 volts and 250 amp hour. This brought about no change in in the output, which remained at 4.5hp, but it gave it a much larger range, and could now travel 130km on a single charge, as opposed to the 65 on the 48 model. Top speed increased to 45kph. At this time the car became known as the Tama Junior, thanks to the arrival of a new larger model called the Tama Senior.

In December 1949 a 4 door version was also released called the E4S-49-2. It was mechanically the same as the E4S-49-1. At this time there was also a change to the grille design, which now boasted 2 wide chrome bars instead of the previous 5 bar design. It also featured a new bonnet design tat was much wider at the front.