Another subsidy is in the works, in the form of a mileage rating of 100 mpg -- allowing GM to make and sell that many more low-mileage SUVs under the cockamamie "fleet average" mileage rules.

WSJ: Obama's Car Puzzle

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.

CNN: Use your Mac to track your money

But they won't sell in large enough numbers to significantly boost their average fleetwide mileage.

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If you don't want to use Excel (and you don't really care whether you can determine your average daily mileage between trips to the mechanic), you've got a couple of other options.

CNN: Use your Mac to track your money

Average new car mileage in the U.S. has increased up to 24.5 miles per gallon in the last year, a large part due to the introduction of electric and hybrid electric cars.

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The iQ's city mileage is 36 mpg, meaning that its average fuel economy pencils out to 37 mpg, the highest of any nonhybrid on the market.

WSJ: 2012 Scion iQ Review: Slow, Whiny, Tiny��but Great to Park | Rumble Seat by Dan Neil

That regulation nearly doubles the mileage requirement for manufacturers, making them boost their corporate average fuel economy (CAFE) from the current standard of 29.7 mpg for cars and light trucks to 54.5 mpg.

CNN: Fact Check: Obama on fuel economy: Your mileage may vary

Your mileage will vary, but I think my profile would fit the average user.

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Its residents, who drive an average of only 7, 000 miles per year, the second-lowest annual mileage in the country, won't get much sympathy from people in Wyoming.

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