The BIRD is coming along nicely Jimbo.
Just for reference's sake, I used to get between 400-450km on a full tank. Rarely got 500+ only on long highway runs.
In Japan, they measure fuel efficiency in the format: km/L The earlier Gen 3s were only every expected to get 6-7km per Liter. Thats 390 - 455km per 65L of fuel.
No matter who I spoke to in Japan. Friends, driving instructors, mechanics you name it, they knew the GTB well and the first thing people would say is 'Nempi waruuuui' which literally means shyte fuel economy.
regardless of this fact, they were the must have car for anyone living in cold/mountainous regions (most of regional Japan) where stability is needed in icy conditions and grunt was needed to get up hills.
Other thing is - Japan has rego 'tax' brackets for cars based on engine capacity. You will notice on your documentation that the EJ20 is actually 1998cc or something just shy of 2.0L.
This is so that owners would not be slogged with the more expensive tax bracket of 2-3L vehicles. Hence the need for turbo variants. Sequential TT made sense as the demand for hilly terrain required more boost at lower revs in lower gears.
Youll never get good fuel economy out of the BIRD. Comparatively, Marks E-tune for example will def get better fuel economy - being the newer variant.