This is an urban legend.
First, the Tama truck was built in 1947, not 1949. The vehicle also had only a 4.5 horsepower motor and had a top speed of 21 mph, and lacked any other power-robbing features such as power steering or air conditioning.
Tama also made an electric car, also in 1947. The figures for the car publish a range of 65 Km (40 miles), not 200 Km (124 miles). The car used the same motor as the truck and had a top speed of only 22 mph. So, given the fact that it had the same motor and similar performance, it is absurd to think that the truck somehow achieved three times the range of the car.
Either way, it's not a logical comparison. It is only meaningful if you know the number and type of batteries in each system. It's a little like a dude in a dually pickup truck with two fuel tanks boasting that he can get better range than my Chevy Spark. But, my Chevy Spark only has a 9 gallon tank. How far will Mr. Pickup Truck get on 9 gallons! The same here. Without knowing exactly how many batteries (which were lead acid) and the total kwH capacity available, a 200 km range (even if it is true) is meaningless in isolation of other information.
Tama became part of Nissan. Here is Nissan's own description of the vehicle:
During the 1940s' switch to a peacetime economy, around 200 Tachikawa Aircraft employees moved to the newly established Tokyo Electro Automobile Co., Ltd., which embarked on the development of an electric car. One reason for this was the extreme shortage of gasoline at the time. In 1947, the...
usa.nissannews.com
I'm not certain of the source of the 200 km claim. However, Tama made both gasoline and electric versions of their cars and trucks. It is possible that the 200 km range actually applies to one of the gasoline models, and not the electric variant. Tama did come out with a mid-sized passenger car in 1949. So, perhaps the 200 km range and the date of 1949 actually apply to this car, but someone assumed it must be talking about the electric truck, since that is the thing Tama is famous for producing and was their first prototype vehicle. That's just a personal theory; I'm not sure of that.