On Fri, 20 Jan 2012 05:47:04 -0800 (PST), "
> wrote:

>Lexus and Hyundai currently have 8. Dodge will soon have 9. Now
>seems Hyundai is upping the ante and developing a 10-speed automatic
>transmission. Good god, where does this end? Soon cars will be
>sporting enough gears to make a trucker blush.
>
>Patrick


I suspect a lot of it is marketing. Once you add a third planetary
gear set you have all sorts of possible ratios. Now that most
transmissions are controlled electronically rather then by simple
hydraulic valves, it's almost trivial to add another "gear". I read
some years back that in many of these transmissions they often
"skipped" one or more of the possible ratios depending on how hard you
were accelerating since most of the time you don't need all of them to
move things along. It would be interesting to talk to a car makers
autobox engineer about this.