G'day all.
Only my second post so be kind please but I have been following this thread and feel I am qualified to pass comment.
I started my training 25 yrs ago (and it still continues) as an Automotive Technician.I have been doing Wheel alignments for the most part.
Here 'Down-Under' things work just the same, despite being upside down and on the correct side of the road. lol.
Some of the following may be arguementitive however, other alignment angles aside, manufactures specs for toe-in are not generally related to handling.
They are, indeed, a direct attempt to 'neutralize' the effects of dynamic loading of steering and suspension components.
Without 'toe' adjustment (in or out) deflection caused rubber bushings, 'road-drag' (rolling resistance), braking and 'Drive-loading' (front wheel drives) cannot be compensated for.
Each vehicle does, indeed, have its own characteristics as does every driver.
As with every manufactures spec that gives a tolerance you can expect to have situations that require using setting to the lower or upper end of the scale.
Since us Ecomodders tend to drive conservatively then it could be expected that our wheel alignment setting could also be conservative.
So, might I suggest that, instead of crunching numbers, you have a look at how your tyres are wearing. The more friction (the 'Enemy') the more exaggerated or uneven your tyre wear will be. To the inner edge, lack of 'toe', to the outer edge, excessive toe. (other angles and driving habits aside remember!).
In other words, if you're are getting good mileage out of your rubber and the tyres are wearing flat then maybe your efforts toward better fuel economy could be more fruitful elsewhere.
Hope my comments help.........Matt