ZRE tanks are 55L and at least 80kg's odd heavier than the ZZEs. There are too many variables to compare the two.
And if you want to know how fuel efficient the ZRE can be. In summer, I use to work on the Westside of Melbourne (I live in South-East). My average was 7.2L/100kms (on the car computer) and best was 6.9L/100kms. Typically, I would drive 600+kms and fill up only 45L max. This included spirited driving every now and then. So the ZRE can definitely achieve lower than this, I think I read someone did..
Since I am not working there anymore and am just going short distances from home to uni and I put a CAI in, my average has gone up to 7.8L/100kms hahaha! Still can achieve 7.1L/100kms but I don't drive far distances frequently anymore, maybe once or twice a week now.
Peter.
EDIT: I love the induction noise!