Decals, bumper stickers and magnetic signs on cars are as common a sight as traffic signs. Putting a company logo on a personal vehicle is a simple way to advertise your business whenever you're driving. In some places or circumstances, however, it's illegal or impractical. A little planning and research can prevent magnetic signs problems.

Will a Magnet Stick To a Car?

Magnetic signs have an advantage over more permanent forms of branding, like decals, as they're easy to apply and easy to remove. Suppose you only want a business logo on your car during business hours; whip off the magnet at the end of the day and your vehicle is personal again. However, there are drawbacks:

  • Magnets aren't designed for high-velocity driving. If you drive highways or interstates regularly and keep your pedal to the metal, your sign may fly off.
  • You have to keep the sign dry and clean. Moisture and dirt can weaken the magnet's grip on your vehicle.
  • Condensation can also do the opposite, fastening the magnetic sign to your car like an adhesive.
  • A big drawback is that magnets only stick to magnet-responsive metal such as iron or steel. If you try sticking a magnetic sign to aluminum or plastic, it won't work. Check which parts of the car can accept a magnet before you shell out for the sign. 

Vehicle Signage Laws

Vehicle signage laws vary across the country. In many areas, there are no laws about advertising on your car with magnets or anything else, as long as you don't obstruct your windows. Other governments take a harder line.

Five California cities, for instance, have passed ordinances banning or restricting business owners from affixing or painting advertising on their vehicles. Businesses that used "mobile billboards" sued on the grounds the vehicle signage laws violated their freedom of speech. The 9th Circuit appeals court disagreed:

  • The cities regulated the act of advertising on vehicles, not the contents of the ads, so free speech wasn't an issue.
  • The businesses could put the same ads on billboards or posters without restriction, which also showed that content wasn't the issue.
  • Local governments have the right to restrict activity in the streets for aesthetic reasons or to keep other drivers from being distracted. 

Special Cases and Restrictions

Even if your jurisdiction allows mobile billboard ads, specific ads may still be ruled out of bounds. Marijuana sales are legal in Colorado, for instance, but vendors can't advertise via "any sign mounted on a vehicle," according to state law.

In New York, you can advertise on your personal vehicle. However, you may have to register it for commercial use if you place a company logo on a personal vehicle.

Some homeowners associations also forbid drivers parking mobile billboards where they're visible. Even if you park at your house, you may need to place the car in the garage, remove the sign or cover it up.

The IRS View

Federal tax law allows you to write off the business use of your car. IRS Publication 463 goes into a lot of detail as to what counts as driving for business. Traveling from your office to meet a client, for instance, is a legitimate deduction; commuting from your home to a meeting or to your office is not deductible.

Putting advertising on your car doesn't change any of that. You may feel that driving to the multiplex and catching a film should be deductible; after all, your car is advertising your business all the way there and all the time it sits in the parking lot. The IRS says no: if the driving would normally count as personal use, putting a company logo on a personal vehicle doesn't affect that.