Originally Posted by Timthom62
Part of the benefit of the dual clutch transmission is that when one shaft is engaged, the PCM and TCM have already enabled the next expected gear on the disengaged shaft. So if you're in 5th and accelerating, 6th gear is already engaged on the opposite shaft and waiting for the clutch to engage. The point being to prevent the lag between shifts that was normal with a standard automatic transmission.
The algorithm for pre-selecting the next gear is not quite so simple.
For example, if you are in 5th gear, 6th gear will not be pre-selected until you hit ~74 MPH.
Gear selection (for the next gear) often takes place at the time of the upshift.