What's the one tech accessory that quickly pays for itself in lower repair costs? Without a doubt, it's the power-folding-mirrors option available on most SUVs and big passenger cars. They can make a vehicle half a foot narrower or more, and that may be all the difference when you zip into your garage in a hurry.

Take the Mercedes GL320 CDI pictured here. It's listed as 76 inches wide; a standard 8-foot garage door is (supposedly) 96 inches wide. (The biggest SUVs are 80 inches wide.) But the mirrors stick out about 3 inches past the car's widest point on each side, and a garage door, framed out by the carpenter, is about 2 inches less. The upshot: Your 20 inches of theoretical clearance becomes about 5 real-life inches on each side, assuming you center the car perfectly every time you park. Enter the folding mirror, which reclaims 3 or 4 inches per side.

If they're sold standalone, power folding mirrors add $100 to $200 to the price of the vehicle. More often they're part of the, say, "convenience group" options package, or they come standard. Didn't buy the power folding mirrors for your current Bigfoot? Some vehicles have a universal wiring harness that includes a connector for power folding mirrors whether or not the vehicle comes so equipped, so you may be able to retrofit, although the cost could zoom to $500. Your dealer's service department should know (double-check online). If not, you can buy third-party folding mirrors that a garage or car electronics store can easily install. Don't confuse the power folding mirror with power adjusting mirrors or the power mirrors that tilt down on the passenger side when you're backing up.

Power folding mirrors are becoming options even on the smallest vehicles, letting them fit into tiny urban garages or avoid being snagged (or vandalized) by passersby. You could, for a lot less money, just roll down the window and retract the mirror on your side. But try and do that with all but the smallest of cars on the passenger side.