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Plug the Quarter- and French Fry-Eating Hole
For the most part, you probably don't think about that gap between your seat and the center console—until you round a corner and swoosh! Your cell phone slides down, trapped in a space too narrow for your fingers to easily grab it. While we're apt to immediately retrieve our iPhones—though please, resist the urge to lunge for fallen items while driving (distractions like this were responsible for 3,331 deaths in 2011, according to the U.S. Department of Transportation)—certain items tend to nest there indefinitely: crumpled gum wrappers, pens "borrowed" from the bank, the loose change you're always hunting for when you reach a toll. After you've taken a few minutes to clear everything out, the next step is to close the gap.

A foam seal used for insulating a window air conditioning unit can be trimmed to fill the space, though it may shuffle or fall if you readjust the seat. Another alternative is the Drop Stop. This neoprene wedge has a slot that fits around the seatbelt buckle, and it moves with the seat, so it won't become the gap's newest victim if you need to move forward a few inches.

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Excavate Under the Seat
Work your way from that dreaded console gap to the space under your seats, and get rid of anything and everything that's under there. The one thing that's safe to keep? A few dryer sheets. Organizing expert Peter Walsh recommends stashing one under your seats to fill the car with a fresh, clean scent.
cup holders

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Upgrade Your Cup Holders
These little beauties aren't just for keeping your hazelnut latte spill-free—they're the unofficial junk drawer (and cell phone holster) of the car. Thankfully, a range of new organizers help maximize this fist-size space, so you can store your phone without having it butt up against your condensation-dripping Big Gulp. Some models even have compartments for your loose change and sunglasses.

Speaking of dripping drinks, Frugal for Life has an easy fix for preventing that sticky residue that inevitably builds up on your cup holders—and causes clutter balls of old gum wrappers, pennies and who knows what else—simply cut sponges (or absorbent coasters) to fit.
car door

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Turn Your Door Pocket into an On-the-Go Cleaning Station
If the cup holder is the car's junk drawer, that little storage slot on each door is a mini Dumpster. It's just so convenient for stashing junk mail and half-full soda bottles while you're on the road. The problem? The trash rarely gets emptied, until it's overfull. Or stinky. That trash nook doesn't have to be reinvented; just streamlined. An empty cleaning-wipes tube can be filled with plastic grocery bags so you can easily grab one, collect any loose garbage in your car, and toss it after you've parked. This pocket can also be a great place to stash a few reusable shopping bags. (I've found it much easier to remember to take them with me into the store when they're right in my line of vision as I'm getting out of the car.)
glove compartment

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Transform Your Glove Compartment into a Mini Filing Cabinet
A thin coupon organizer (or recipe file) is an easy way to have fast access to your car's most vital papers. Registration, insurance information, car repair and maintenance receipts can all have their own tabs, recommends Lorna Kyle Boot of the blog, That's the Coolest Thing!, and most styles fit comfortably inside a glove compartment. You could also stow a few napkins there (read: 3-5, not the two dozen or so that often get crammed there "just in case" after a drive-thru run) and a car charger for your cell phone.
car trunk

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Tame Your Trunk
Watch the throne, Grumpy Cat—blogger Heidi Castro's minivan could be the next viral star. Okay, that may be a teeny bit of an exaggeration, but Castro's so used to being stopped and quizzed about her organization strategies while loading groceries that she posted a guide on her blog, The Castro Family Happynings, and images of her trunk are repinned endlessly on Pinterest.

You may not need Castro's level of organization, but her trunk illustrates a few key pointers for keeping things in order. If you need as much floor space as possible, you could try attaching plastic organizers to the backs of the seats, like she did. Or, if your biggest problem is items that jumble together everywhere, try using a multiple-compartment, collapsible bin. Velcro attached to the bottom can help keep it from sliding around.From there, consider giving yourself a "two weeks" rule: If it's not part of your emergency kit and you haven't used it in 14 days, it needs to exit the vehicle.

Next: How to spend less on gas