Originally Posted by Driver72
Regarding CVT's I don't think they are strong enough.
And as stated in the OP, I agree, I think 8 speeds are too much.
When manuals and autos were 4 speeds, having a 5 speed was a revelation. Then when 6 speed autos AND manuals came out, it made sense for better acceleration AND better gas mileage.
Then Mercedes (I think they were first) brought us the 7 speed auto.
Personally, I don't know of too many people who thought, "awesome, 7 speeds, that's going to make a HUGE difference and is welcomed."
Mercedes skipped 6 speeds. And there 7 speed autos DID improve performance and gas mileage in their vehicle line. But would it of improved performance and gas mileage if they would of gone from a 6 speed to a 7 speed? I'm not so convinced.
Lexus wanted to upstage MB by going to the 8 speed auto.
And I don't think I've read a single review of it, where testers were rejoicing over having 8 speeds. Quite the contrary, where they've felt it too much.
So too me, nobody has "rejoiced" adding additional gears since 6 speeds have become common.
It just makes for too many gears.
4 underdriven gears
1 slightly overdriven gear (.90)
1 significantly overdriven gear (like .75) for highway crusing
I personally think that's perfect.
So IF I was to of had a say in the new ZF 8 speed auto, I would of made ALL the advancements they made with it, and all the robustness of it, and made it a new 7 speed auto AT MOST, and possibly just made it a better 6 speed auto. And in doing so, they probably could of made it 20-30 lbs lighter (since they made the new 8 speed the same weight of the current 6 speed).
Driver72 makes some good points. I still think 8 speeds can be a very good thing, but it boils down to what ratios you choose.
Its been a while, but if I remember right, the Lexus box had too many overdrive gears, so they couldn't be used effectively in sporty driving. However, if you read the reviews of the new Porsche 7-speed Dual Clutch, magazines hail it's perfection of using most of the gears in short ratios and one tall gear.
With an eight speed tranny, it can allow several different personalities in one box. In regular drive, most BMW's start out in 2nd, for FE and cruising. DS is first gear. With this logic, you can expand that concept to have different strokes for different folks.
Bottom line, eight speed can allow for a lot more options, IF the ratios are right and software is programmed right.