Ok folks, I managed to dig out the brochure which contains "some" info on the ratio question.
There are 2 different boxes fitted to the 1.6vvt 115 engines depending on wheter it's a Scenic (JH3 144) or Grand Scenic ( JH5 125)
The speeds in each gear @ 1000 rpm for the JH3 box are - 4.760/8.662/12.732/16.168/19.878 .
The speeds in each gear @ 1000 rpm for the JH5 box are - 4.430/8.065/11.850/16.995/20.126 .
It appears the JH5 box has a slightly lower set of ratios in 1st, 2nd & 3rd but then 4th & 5th seem slightly longer. Possibly to contend with the extra weight of the Grand.
The 1.9 dCi (ND0 & ND0 002) box has a completely different set of ratios.
The speeds in each gear @ 1000 rpm for the ND0 box are - 5.623/10.433/15.280/20.294/26.222/31.820 .
All the ratios seem taller on this box but there is no onfo in the brochure for any of the final drive ratios. This might account for the differences in the two 1.6vvt boxes, but as the ND0 box is a Nissan derived unit it can't really be compared to the other one. 6th gear on this box does "seem" like an overdrive though.
I hope this hasn't confused matters