[JimD]

One of the incomplete stories or lies told about transmission type is that automatics get better mileage. That bugs me because a manual transmission is inherently more efficient in energy transfer than a conventional automatic which has losses in the torque converter (which is why it needs a cooler that a manual doesn't need). But manufacturers seem to disbelieve I know how to downshift when necessary and they gear my manual to turn more rpm in top gear than it would if it was an automatic. The higher rpm overcomes the inherently higher efficiency of the manual and the automatic gets better gas mileage.

DCT is mechanically the same as a manual with no torque converter losses. But it gets geared like an automatic so it would be theoretically equal to the manual and as implemented by car manufacturers better in terms of gas mileage. Mechanically it is always better than a conventional automatic.

So do not accept anybody telling you that an automatic is better for gas mileage. Lower rpm is better but transmission to transmission the manual is better. But unfortunately we cannot easily have them geared the same. You could change the rear end on the manual (or put on bigger diameter tires) but then you loose acceleration. What we need is a taller final drive ratio in the transmission. 5th is so close to 6th in my car I often skip it. We need a wider spread. If I really need to accelerate at highway speeds, I drop to 4th.