For car owners, spring and summer are the most popular seasons to wash and wax their cars. But for their cars, winter is the best season - especially in cold climates when dirt, corrosive road salts and melting snow can do a lot to destroy automobiles.

The International Carwash Association, a not-for-profit trade association committed to educating the motoring public on vehicle maintenance, says that motorists wash their car less in the winter months than in summer. Yet cars require more washes in cooler months - and when that doesn't happen, the resulting damage often goes unnoticed until it's too late for a cheap fix.

"By far, salt is the biggest car culprit - it can attack even the toughest paints and finishes if not washed off consistently," explains Mark Thorsby, executive director of the International Carwash Association. "Nearly $24 billion a year is spent battling automobile corrosion damage. This winter, getting your car washed at least once or twice a month - or more if you see or feel build-up - is essential to protect your investment."

Drivers should be wary of the following car culprits this winter, says the International Carwash Association:

• SALT. Most icy roads are treated with a corrosive mixture of sand and salt often in the form of sodium chloride. In recent years, another corrosive salt mixture - sodium magnesium - has been used on roads, which some experts say is even more corrosive. Some state transportation departments have even stopped using it due to its harsh impact on cars. Whichever mixture is used, salt caked on the undercarriage can promote rust, especially in older vehicles. It can also affect how well the car drives.
  
• ACID RAIN. According to studies compiled by ICA, it is critical to wash a vehicle immediately after a rainfall. As rain falls, it collects pollutants from the air, a concept commonly referred to as acid rain and triggered in North America by industrial and automotive pollution. The water eventually evaporates leaving a thin film of pollutants that can damage a car's finish permanently.
  
• ENVIRONMENT ELEMENTS. Bird droppings, road grime and tree sap can also mar a car's shiny finish, leaving it dulled and imperfect looking.

The International Carwash Association suggests car owners and drivers take the following actions this winter:

• Be a step ahead of winter. Visit a professional car wash at least once or twice a month - or more, depending on local weather conditions.
  
• Details, details. Professional detail services can restore a car to showroom quality, or very close to it. The ICA recommends detailing services at least once a year - or twice, if an ultra-clean look is desired year-round. A good time of year to get a detail is in spring, to remove the winter road grime from a car's interior and exterior - but anytime is better than not at all.