It's been a bit more than a month now since I began my experiment with coasting, and it is with surprised delight (and perhaps a touch of smug self-congratulation) that I report the results: It works! It really works!
I've done two mileage checks so far. The first produced a figure of 37.5 miles per gallon. The second came in at 36.79 mpg. I will confess to having slacked off a bit after the first mileage check, and am now driving with renewed dedication to the fine art of extending inertia to its safe limits.
So, how much fuel economy have I achieved? According to this website, a 2006 Scion xB should get overall gas mileage of 28 mpg. Not having done a baseline mileage check before the Great Coasting Experiment began, I can't be sure, but I believe I'd been getting around 30 mpg previously. So this technique is definitely paying off. At 30 mpg, driving 12,000 miles in a year would require 400 gallons of gas. Up the fuel economy to 37 mpg and the gasoline consumed drops to a smidgen over 324 gallons. At four bucks a gallon, that's some decent savings right there -- $304. Since the price of petrol seems determined to continue its ascent toward the stratosphere, future savings are looking even better.
And now, having tested my hypothesis and succeeded well beyond my modest expectations, I'm gung-ho to keep on coasting. Is 40 mpg achievable? Let's find out!