I definitely get 29.5 MPG with my normal driving style consistently. I keep track of every tank of fuel (for reasons other than mileage, it's a good barometer for problems with the engine too). 29.5 is my yearly average, in winter it averages 28, in summer, it's nearly 31. When I was doing the testing it was spring, so I was actually getting my average 29.5 driving normally. I ran through two whole tanks on the attempted-economy driving style, and only saw the 1 MPG increase on both tanks consistently, went back to my old style of driving, and right back to 29.5. I really forced myself to attempt to do it 'the right way' too, no cheating, though now that you say featherfooting isn't all that great, that was primarily what I was doing, just going slow and taking it easy.
I think I'm definitely more interested in (and capable of) mpg through mods. My last car, I had rewritten some code in the ECU to help with fuel economy
unfortunately the newer the car is, the more complicated and locked down it becomes, so ECUs are less accessible; boo.