ive found a trend in my car. it's basically always KMs/10 + 10 = Litres of fuel
so 350kms = 45L filled up
400km = 50L filled up ... and so on
my 33's usage was similar
so far ive only had one tank which was used for pure thrashing and i did about 250km in 55Ls
freeway driving is typically a lot better than the formula above.. the other day after filling up, i drove 130kms. then i pulled over and filled it up again, and i only put in 16Ls..
edit: i just realised that the above does not apply to u as i have an rb25det in my 32.. lol sorry.