My CrossTrek is 3200lbs and has 148hp and 145ft-lbs torque. I don't understand your issue.
It's not the power to weight ratio that is the problem...it's the method of delivery.
Small-displacement turbo engines will rely on the turbo boost more often for routine acceleration. Turbos are for power, not fuel savings - the fuel saved at idle is marginal!!!
That's my point - small, turbo engines with auto trannies will not deliver great real world fuel economy - too many variables (wind, weight [incl AWD hardware], highway passing, etc) cause the engine to go into higher boost more often (which is more efficient for combustion, but uses more fuel to do so).
Manual transmissions give the driver the POSSIBILITY (not the guarantee) of better fuel economy because they can keep the engine in its most fuel efficient range. This is why Subaru's new CVTs and Nissan's long-used CVTs do so well with fuel economy. People, stop hating CVTs. I'd rather better technology in transmissions than newer engine technology at the moment - that's why Mazda went for the Skyactiv treatment.
If you don't believe me, for example, there's the Veloster - the Manny gets 27 MPG combined and the Auto gets 25 combined with a 1.6T, FWD, at 2584lbs curb weight. There is no way that a taller, heavier, auto only, 1.4T Encore even in FWD will get better COMBINED mileage than the Veloster.
Let me be clear - I LOVE turbocharging...but for performance - not fuel economy. Calling it more "fuel efficient" is just a marketing lie. Compared to older V6s with terrible auto trannies? Sure...but compared with modern V6s in real world driving? No chance. Not to mention that they're more expensive to make, maintain, and repair...I'm not convinced.