[digitaldissent]

Some members are getting discouraged with mods and I've been thinking of foibles that could be associated with the "magic" of the Scan-Gauge.

The "up-shot" of the electronics is that they give instantaneous readings, without burning allot of fuel for results. One concern is that "scanners" may be seduced into taking readings before their vehicle is in a position to provide useful data.
Here's the rub.

-A vehicle requires 22-miles (35.5 km) of continuous driving before it reaches equilibrium temperature.

-Tires will come up to temp in about 5-miles (8 km ),however coolant, engine oil, transmission and differential require a full 22-miles before their viscosity reaches it's final status.

-Any testing conducted without the "warm-up" has the potential of such a great amount of variables as to render results, dubious at best.

"Ideal" testing, is conducted at 75-degrees F, no wind, flat road surface, no turns, and "special" lubes".( don't ask!).

-City vs highway mpg can vary by a factor of 100%.

-A 4-mile cold start test could show 40% below your actual mpg.

-A 2-mile test could show 55% below your actual mpg.

-A 1-mile test could show 75% below your actual mpg.

-Wind can affect mpg by (negative) 17%, to (positive) 19%.

-Road grades can affect mpg up to 55%.

-Rain can cost 1 mpg.

-A 50-degree F test day will cost you 5% mpg. If temp drops to 20-degrees, you’re looking at a loss of 11%. It's easy to lose 3.5 mpg during any winter.

I hope everyone is tracking "tank" mpg, to go along with their Scan-Gauge results.

I'm not into anybody wasting any additional fuel during testing, but there's a reason for the warm-up, and I'm afraid many modders will suffer needless disappointment if they inadvertently stray from the rule-book.