As confined spaces, autos can seem to breed some really ugly odors. So what’s a car owner to do to get rid of them?

Start with the easiest things.

Be sure the car is clean. Thoroughly scour the interior and get it free of dirt and debris. Vacuum and wipe every surface you can reach.

I know this sounds like common sense. But you’d be surprised at the things people discover in their vehicles.

One woman found a beef roast in the trunk – badly spoiled, obviously, that she had forgotten from a grocery trip. Another spotted cheese sticks that her children had squirreled away between seat cushions.

If the smell remains even after cleaning, try to determine what is causing the smell. Many smells are the result of mechanical problems. Indeed, they can signal that something is wrong.

For example, if a driver smells something sweet around the car – sometimes the smell is described as sweet like maple syrup – it can come from leaking engine coolant.

Today’s engine coolants have ethylene glycol in them, and if this fluid is leaking – from the radiator, a hose under the hood or in a heater core – a sweetish smell is a quite common alert.

Another example: A driver who smells gasoline around his or her vehicle had best get to a service technician. Why? Because a raw gasoline smell can indicate a dangerous leak.

Simply put, it’s never good to have flammable fuel like gasoline dripping out where an ignition source could find it.

Sometimes the odor occurs when turning on the heating or cooling system, especially in humid weather, because as this system feeds proper-temperature air inside the car, it condenses moisture in the air.

If the moisture builds up in the air conditioning system – maybe because the air conditioner innards aren’t draining this moisture properly – mildew and mold can grow, and passengers can smell it.

Have the air conditioner system carefully examined – from fresh air intake ducts to drain pipe – and look to see if there are plugged areas and proper drainage.

An anti-fungus agent might need to be applied to the air conditioner’s evaporator. Remember, mere air fresheners won’t affect microscopic crud.

You also should check the carpeting on the passenger side, under the dashboard and near the center tunnel of the car.

Sometimes the moisture buildup in the air conditioning evaporate can be so severe that water leaks out at times onto that floor area.

This leakage, in the confined interior of a car, can smell, too, and stay there in the carpet unless it’s well-cleaned.

One way to try to avoid problems with mildew in an air conditioner is to regularly run a car’s ventilation fan on high heat for 10 to 20 minutes, even in summer. There also are some after-market offerings of blower systems that some car owners wire into their troublesome vehicles.

These after-market systems run a car’s ventilation system fan for a bit after the vehicle is turned off. For more on this kind of product, see www.airsept.com.

I do not recommend trying to cover up smells in vehicles with other smells from air fresheners, though this is a common tactic in the auto business. This can merely add another smell to the mix inside a car and compound the problem.

Then, instead of trying to remove one odor, a car owner has a sometimes sickening mix of two smells to get rid of.