First Look: CarMD Takes Your Vehicle's Pulse

As the saying goes: Trust your friends, but cut the cards. So even if you trust your auto mechanic, consider using the $90 CarMD to make sure you're not being charged for unnecessary repairs.

Just a little bigger than a standard cell phone, CarMD plugs into the On-Board Diagnostics II port of any 1996 or later model car or truck. (In most vehicles, the OBD II port is under the dashboard.) The unit gave my wife's 2001 Honda Civic the green light just minutes after I unpacked it. The device shows a green check mark if your car passes CarMD's diagnostics, a yellow question mark if it finds a pending problem or inconclusive results, and a red X if the vehicle needs service. CarMD says that a yellow or red light means that a car might fail a state emissions test.

To get the lowdown on glitches the unit discovers, you load the CarMD software from a CD onto your PC and plug the device into your PC's USB port. The CarMD.com Web site loads automatically in your browser. After you register your car (including its vehicle identification number), the site produces a report describing the most likely fix, other possible fixes, and the relevant diagnostic codes.

Click one of the Fix tabs to see the items in need of repair or replacement, unit cost, quantity, and total cost of the repair. The site even adjusts prices for four U.S. regions. You're allowed three reports each month on up to three vehicles, but you can use CarMD's green, yellow, or red indicators on as many vehicles as you like.

While we're not auto experts, CarMD seems like a smart, valuable investment. Just having more information on the health of your car will give you peace of mind, whether or not it ever saves you a nickel.