Many states in the U.S. now require smog inspections to make sure your car is putting out pollution that's under the maximum amount allowed by your state. New technologies are coming out all of the time to make it easier for you to pass this test, however. You can either add emissions-reducing equipment to your existing car or get a new one that doesn't have an emissions problem at all.

Vehicles with Lower Emissions

There are a variety of cars out there that don't put out any emissions at all. The most well-known of these are electric vehicles. You can connect these cars to a special electric socket in your house in order to charge them up. They can then run on clean electricity without burning anything.

There are subsidies from the U.S. government that can make these cars far cheaper if you're thinking about upgrading a car that just pollutes too much. This includes up to $7,500 in tax credits for certain cars. This can make electric vehicles more affordable than they seem at first.

So called "plug-in" electric vehicles aren't the only kind either. Some vehicles can actually run on compressed air instead. You have to compress air into its compartment while it's at home. Some versions of these cars are hybrids using both a traditional combustion engine and a compressed-air version for power. These will often have much lower emissions as a result.

New Catalytic Converters

Another approach to avoiding having your car spew smog everywhere is to upgrade an existing vehicle by installing a more advanced catalytic converter. Traditional catalytic converters force combustion byproducts through channels with rare metals in them. The pollutants combine with the metals, eliminating large parts of the pollution.

New approaches are expanding the surface area of the microscopic channels in catalytic converters, making them more efficient. This has a number of positive effects, including making the tech cheaper since 80 percent less metal is needed in the new converter compared to traditional ones.  The new devices are also known to be more efficient at removing the pollutants from the air. These improved converters can also boost fuel efficiency.

This means that by using a better catalytic converter, not only will you be able to more easily pass a smog test, but you'll pollute less overall. It's estimated that this converter could improve fuel efficiency by as much as 3 percent. The new converts are also known to last as much as 35 percent longer than the more traditional kind.