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At 51 cents per mile, the tax deduction small business owners pass up by not keeping driving records adds up fast. With CarCheckup, a device that plugs into the onboard diagnostic port (found in all cars made after 1996), tracking mileage becomes simple.

The device records distance traveled every time you start up your vehicle, and it plugs into any PC via USB to download mileage records to your computer in CarCheckup's software or Excel.

"It tells you how far you went and allows you to mark each trip as personal or business," founder Jen Funkhouser said. "The IRS really demands documentation; this will allow you to generate that."

Bonus: You know how your mechanic has that computerized device that helps him figure out what's wrong with your car? CarCheckup also reads those error messages, so you can finally get that "check engine" light turned off.

Mac users and hybrid drivers, skip this one for now -- the company's still dealing with the unique demands of these computers and cars.

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LAST UPDATE: Apr 13 2011 | 1:44 PM ET
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