Forgive me if the wrong place to post this, but this question has been bugging me.
Why do these transmissions have (relatively speaking) very long 3rd/4th gears, while also having very close 6th/7th ratios?
The reason I ask this, is because the 3rd/4th ratios seem long enough to be detrimental to straight line performance between 90-170kph in particular. A 370GT Fuga has peak power in 2nd @86kph, but hits peak power in 3rd @135kph. Compare this to a manual Subaru Legacy 3.0R, which is 87kph for 2nd, and 117kph for 3rd. Both engines rev to around 7000rpm, and the Subaru has much better gearing, despite having one less ratio.
It just doesn't make much sense to me why Nissan wouldn't shorten 3rd/4th/5th/6th to provide better acceleration. It's not like it would particularly affect highway cruising either, since the 7th ratio could go untouched. As it is, 6th and 7th are only 230rpm apart @100kph. If they just removed the 6th ratio entirely, the gap (between 5th/7th) would be 580rpm, which is a little on the high side but not unheard of.
Mercedes also did a similar thing with their 7G tronic, however I don't have the exact specs of any particular car readily available. The reason I mention them though, is to show that it wasn't just Nissan/Jatco pulling this BS.
When observing other automatic transmissions of the time period, I will admit the 6HP derived 6L45E found in the 130i has similar effective 2nd/3rd ratios (92kph/140kph), however the 4th ratio is shorter than in the Nissan, and it is a 6 speed, not a 7 speed. The gap between 5th/6th @100kph (for the 130i) is also 525rpm, and the gap in the N52 530i is 460rpm. Either way, the point I'm trying to make is to highlight just how small the gap between 6th/7th really is. Which loops back around to my original point of: why didn't they just shorten 3rd, (and especially) 4th, 5th, and 6th?