Since our 3.0L Duramax is still in the shop, the only thing I have to talk about is the underwhelming fuel mileage of the 2.7L 4cyl turbo.
My question is: if 4-cylinder can't beat the 5.3L V8 in towing or fuel economy, what's the point GM? Just discontinue this engine. It offers no advantage over the 5.3L that I can see. That's just my $0.02.