The Exterior

A warm, sunny spot might seem like the perfect place to wash and dry your car, but it guarantees streaks. Wash in the early morning or evening, or in a shady area.

Rinse it

Hose off loose dirt.

Life the windshield wipers and spray the cracks below both windshields.

Blast the undersides of the wheel wells and the hubcaps.

Wash it

Make sure your wash mitt is clean. "We've seen people ruin their finish because they didn't rinse off the grime on the mitt before washing it," says Robert Traicoff, supervisor of paint materials for the Ford Motor Company.

One-eighth of a cup of mild dishwashing liquid, like Dove, in a bucket of water is fine for unwaxed finishes. Starting with the roof, soap an arm's-length-size section with your wash mitt and rinse it immediately. Then tackle the hood, the sides, and the trunk, in that order, using the same method, so you go from most to least clean for the sake of the soapy water.

To prevent streaking, don't suds up the windows (you'll wash them separately).

Use a separate sponge to scrub only the especially grimy areas: the windshield wipers and the tires. Save the right front wheel for last because it gets the dirtiest — it hits the puddles and loose gravel on the side of the road.

To remove tar, saturate a cloth with a mixture of 1/4 cup vinegar and 1/2 teaspoon linseed oil; rub into the tar and remove.

Rinse again

Sluice off your car, making sure to power the soap out of nooks such as the rim of the gas-cap cover, under the door handles, and the innards of the side-view mirrors. Soap seeps out and streaks the car — usually moments after you've finished drying the car and put everything away.

Dry it

Before water spots have a chance to mar the finish, use a towel to mop up the surface. Fold the towel as it gets damp.

If you have a chamois, use it to mop up any remaining dampness.

Remember to dry spots like the roof line just above the windows, which could spill excess water later when you move the car.

Do windows

Bugs, grease, and grime make auto glass harder to clean than the windows in your house. A detailer's favorite for cleaning windows and bug-spattered headlights is a solution of one part white vinegar to two parts water.

To avoid streaking, give the window weather stripping a few hours to dry before you roll down the windows.