You're right, however those only work at higher speeds, hence the "especially with city driving" :)
From wikipedia : A Lock-up clutch is used in some automatic transmissions for motor vehicles. Above a certain speed (usually 60 km/h) it locks the torque converter to minimise power loss and improve fuel efficiency.
It's typical to omit locking while the transmission is cold, some transmissions may not lock the first gear, or may not lock at lower revs, or at slower speeds, but generally the lock is there and it's just software that controls locking. You can rather safely assume that on most modern cars and in general conditions the torque converter will lock starting from the first gear.
The lock-up only locks up in very limited conditions, especially older ones. There's basically a few specific speeds with a 10km/h margin that locks up.
"We’ve combined the best attributes of conventional automatic, continuously variable and dual clutch transmissions. The transmission locks up to couple directly with the engine over a far wider range than other automatics. This delivers a significant improvement in fuel economy and a more direct, manual-like power delivery and driving feel. Shifts are quick, accurate and smooth across the six speeds."
So, as they mention, this transmission is unique. It does, however, not lock up in all conditions - it remains unlocked until you hit 8mph. It sounds like an interesting transmission, but this is not the "norm". All conventional automatic transmissions should be able to do this, although it results in very different wear patterns (brake rings and clutches in the transmission will see much greater wear). It is not quite as interesting as a dual shift transmission, though.
(Having looked at a picture of the transmission, ignore the "combined the best attributes of..." - it appears to be an entirely conventional automatic transmission with a very different operating profile.)
It locks up after 8 mph probably because if it locked up at any lower of a speed, the engine would be too close to stalling.
Also, the ZF 6HPxx (and newer) transmissions behave the same way. My 2011 335i will lock up in first gear (probably around 10 mph, but it depends on the load). This transmission has been used by BMW since at least 2006. A derivative of it is also used in the Ford Mustang now.
I should try a car with one of those transmissions, then. They sound quite interesting. While I have driven quite a lot of cars, I have never dealt with such a transmission, but it sounds both nice and efficient. How's the comfort tradeoff? I believe the lock-up was initially avoided due to comfort, as people liked the "gooey" transition between gears.
I'll keep that transmission in mind next time I go shopping.
I also drive a CX-5. When I test drove it, one of the things that stood out to me was how it felt "heavy" when taking your foot off the gas. I guess that was just the engine breaking that I wasn't used to on my previous vehicle. Over the last year I've averaged 30-31mpg (mostly highway), which I don't consider too bad for an AWD compact SUV.
Yup, and it is also nice that if you just touch the brakes when going downhill the AT downshifts to engine-brake stronger. I can also feel when the converter locks up when accelerating. Particularly when the engine / AT are cold the acceleration is not ideally smooth because of this (well, it is still much smoother than I can do with my other car with MT).
