By setting up a few simple Excel formulas (nothing more complicated than addition and division, you can see what they look like in this sample spreadsheet), you can not only track your maintenance data (what the mechanics did, when they did it, how much it cost, and what the mileage was at the time) but also see your average daily mileage during each period between servicings.

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The center console screen states one thing, the instant economy gauge states another and, the simple math division test basically (logically) states the CORRECT gas mileage, which is not off by a few miles per gallon but, by many.

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