Quote:
Originally Posted by Ron Jeffries
Part of what I like about my 2013 135is convertible is the DCT. I just think it's technically cool, and of course it's directly hooked to the wheels in a way that most ATs can only dream of. But the 8AT in the m240i that I tested was just fine, and I rather like the fact that you can replace an AT for much less than the 15 large it would cost you if the DCT failed.
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FYI, in more sporting modes, the ZF 8AT in the M235/240 locks the torque converter in all gears beyond 1st. This means there's a direct connection, just like the DCT and 6MT. It's largely why it can shift so fast. The locked torque converter does have some weight and inertial resistance, but it's really no more heavy than a DCT dual clutch assembly and probably not much heavier than the 6MT's dual mass flywheel and clutch assembly.
The modified ZF 8AT used in the new M5 only uses the torque converter for the first few feet of driving in 1st and then it's completely locked. This is the future.
Like you pointed out, the ZF 8AT is a bit cheaper than the DCT. It's also far less complicated than the DCT. The ZF 8AT is still a pricey piece though and is about twice as much as a new 6MT gear box ($7,000-8,000 vs $3,500-4,000).