You confused me with Diesl. I *do* get 40 mpg with my DSG.
2500-3000 is not "spirited driving," in my opinion. That's normal driving and shifting patterns. It's also close to where my DSG shifts, FYI. When I do spirited driving in my BMW I don't shift below 5K and more often closer to 6500K (redline). Sometimes I wind out my bug, but I still find myself shifting around 4K. It's pointless to wind a TDI out, in my experience, the torque curve is pretty flat.
If I put my DSG in "sport" mode I get shifting behavior similar to when I hot foot my bug and I'm sure without checking that my economy plummets accordingly, which isn't something I care about when I'm driving like that. And that's Diesl's point. Pushing either car to the top of the power curve, regardless of transmission, the FE differences are going to be marginal at best.
You refuted your own example. You compared two different cars, with different weights, different wheels, and different driving patterns. If you actually look at his fuelly data he drives over 30% in the city, which likely accounts for his lower FE more than his DSG.
I barely drive in the city. I pull out of my gate, drive about 100 feet, take a left, drive about 4 blocks, take a left, and merge onto the freeway. When I get off the freeway, I merge onto a highway, go through a few lights, turn left, drive two blocks, and turn right, and drive 6 blocks to my work's parking lot. When I drive the bug I shift less than twenty times. I detailed my commute, so you're welcome to check my math of the shifts I would have to do on it. I haven't ever bothered, it's immaterial to my day.
The only time I'd see a FE argument coming into play is for someone driving around in stop and go traffic more often than a TDI owner should be doing.