How do I know my car is getting its best mpg?
The American addiction to automobiles is legendary. In July 2009 alone, the country logged an estimated 263.4 billion vehicle miles, up by about 5.8 billion from July 2008 [source: U.S. Department of Transportation]. Of course, that was down from July 2007 — the top-ranked July driving month to date in U.S. history — when odometers around the country clocked an estimated 267 billion vehicle miles. Unfortunately, those countless hours spent trapped behind the wheel of a car often took place under less-than-ideal conditions. That’s because about 168 billion of them were spent driving on urban roads and streets. Seeing as how most big-city dwellers can wax eloquently on their particular locale’s traffic woes, it’s no surprise that many also obsess over their car’s gas mileage. So the question is — how can driver
