Thanks for piping up, Detail Man! If you have any certain techniques that you do/use, please post.
On the "how long must the engine be off to save fuel vs. idling" question-- have there been any studies/testing done to see how much fuel is used on startup for a given engine? Is there any tech data available? Then it could be compared to the gal/hr used at idle (Scangauge computes this, right?) to see how long it takes to reach the break even point. Are there any other threads on this topic?
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Update! I just filled my tank tonight: 338.7 miles and 8.878 gal. 38.15 mpg. This seems to be within a reasonable margin of error compared to last week's 37.2 mpg. I'll be continuing the techniques I'm currently using for another tank or two (and keeping y'all posted), and meanwhile looking in Radio Shack and such places for a good switch to make a kill-switch. I kind of want one anyway for theft prevention, since I tend to leave my keys in the car (both while delivering, and there's usually a spare key inside the car somewhere).