Dear Every one,
I also do have vitz with the same feature & i did find so many views about its gear denotations.
If we just discuss about D,S & B then all three of them are altogether three different gear trains. Automatic Gears are often known as planetory gears due to the structure, design & the phenomenon on which they are based upon.
The debate will get too long if we start discussing about Planetory gears hance I would just simply define that while driving on high way it has D option to be engaged. This particular gear train has more number of gears in it & has the capacity to gain acceleration through a boosted pressure initially. It helps reaching the top speed with out loading your engine much.
There is quite a big misconception about S, that it is sporty gear so it has to be engaged whren your car is over 100 KmpH. Please donot do that if you love your car as it constitutes of power gears which are required to handle low load situation & can help car in gaining initial acceleration during race or something. It is not be engaged over 100 kmph speed. This may seriously damage your auto transmission gear box because it is not meant to handle very high engine rpms.
B is the anti braking gear & is supposed to be used when coming down from altitude. This is to avoid extra usage of brakes during such journeys to let brakes stay cooler & effective.
Hope i have given what i knew exactly. I am personally a professional mechanical engineer & do have some ordinary automobiles knowledge that i tried to convey.
