If you listen long enough, you'll hear a lot of things about how you should drive and take care of your car. But if you stop and think about it for a second, do you really trust the people who are giving you this automotive advice? Are they the same folks who told you to buy Enron stock? Or who told you that Iraq is the perfect place for a relaxing holiday?

What we're saying here is it is time to take a critical look at what you know about your car, because what you don't know can hurt you, and in a painful spot, too -- right in the wallet. So with the advice and counsel of the service specialists at Chrysler, Jeep, and Dodge, let's take a look at some long-held automotive beliefs and try to determine whether they are myth or hoax... or actually true.

Myth, hoax, or truth?: You should always warm your car up before driving on a cold day.
Answer: Myth. Although the majority of the driving population may consider this to be true, it can actually cause damage to vehicles if done continuously. (Instead of letting your car warm up in your driveway, drive it slowly and easily the first few miles until it comes up to operating temperature.)

Myth, hoax, or truth?: You should not blast your vehicle's air conditioner when sitting in traffic or while driving at more than 60 miles per hour.
Answer: Myth. Vehicle heating, ventilation and air conditioning (HVAC) systems are engineered and tested to operate in even the most severe types of driving environments. The air conditioner has cooling fans and a condenser that allow it to operate even under these stressful conditions, so blast away.

Myth, hoax, or truth?: It is possible to check your tire tread with a penny.
Answer: Truth. You should use a proper tire gauge to check tire pressure, but it is possible to check tire tread with the use of a penny. Simply pinch a penny between your thumb and forefinger so Lincoln's head and "In God We Trust" are showing. Insert the penny into a tire tread groove. If the tire covers any part of Lincoln's head, then your tires should have a safe amount of tread. If you can see Lincoln's head in its entirety or any parts of "In God We Trust" are showing, it is time to invest in a new tire. Be sure to check all tires and in different locations on each tire because the amount of wear can vary from tire to tire and from inner tread to outer tread.

Myth, hoax, or truth?: If you still have fuel in your gas tank when you refill it, use the same grade of fuel that is currently in the tank.
Answer: Hoax. As long as you use unleaded brands of gasoline, it will not harm your vehicle if you mix different grades of fuel.

Myth, hoax, or truth?: Avoid keeping your vehicle at a constant speed during the first 500 miles of a vehicle's life.
Answer: The waffling Chrysler folks won't answer this one definitively either way, but most new vehicles no longer require drivers to vary their speeds during the first 500 miles of a vehicle's life, known as the "break-in period." If your vehicle does require the "break-in period," then you should avoid keeping a constant speed during this time. Even varying your speed by several miles per hour should do the trick.

Myth, hoax, or truth?: Premium gasoline is best for your vehicle.
Answer: Hoax, if your vehicle is designed to be run on regular gasoline, then filling your tank with premium will do nothing for you but send you to the poor house. However, if the manufacturer suggests premium fuel for your car... well, you can probably figure it out from there.

Myth, hoax, or truth?: Do not park with two wheels on the curb, as it will destroy the vehicle's alignment.
Answer: Neither; this is true, only if done continuously. Service specialists say that repeatedly parking a car with one side's wheels up on a curb to provide more space for passing cars can cause excessive wear or stress to tie rods and suspension bushings and could create alignment issues, and you don't want those. Trust us.

Myth, hoax, or truth?: If the steering wheel shakes when you drive, there is something wrong with your brakes.
Answer: Maybe myth, maybe hoax, maybe true. (Geez, are these Jeep, Dodge, Chrysler people passive-aggressive or what?) While they won't nail this down completely, you can bet if the wheel shakes as you depress the brake pedal, it may mean your brake rotors are unbalanced. If the wheel shakes as you drive, it may be the result of a wheel balance or steering-related issue. If you shake will you drive, you might be withdrawing from caffeine or chair-dancing to the reggae beat.

Cleveland-based auto journalist Luigi Frachini can't decide whether his own career is a myth or hoax.