My 1998 Honda Civic LX is equipped with the 4-speed automatic transmission. Before I looked this up, I decided to count the number of upshifts from a stop, and I counted four, not three. This mystery "fifth gear" happens when the engine speed is around 2000 RPM in 4th and the shift brings it down to around ~1400. The kickdown for this "gear" is very sensitive – even slightly pushing on the throttle "downshifts" the car to fourth and the engine speed continues from 2000, rather than ~1400.
Why is this?