2007 Ford Focus SESClick to enlarge picture

The 2007 Ford Focus not only delivers excellent fuel economy, it is also rated as a Partial Zero Emission Vehicle (PZEV).

Auto manufacturers have developed a slew of technologies that have elevated the conventional gasoline engine to new heights in efficiency so buyers concerned with the environmental impact can go green on gasoline.

More precise engine control computers and related programming coupled with refinements in injector design that provide more efficient spray patterns empower today's gasoline engines to burn fuel more completely than ever. On the post-combustion side, improvements in catalytic converter technology ensure any byproducts still in the system are thoroughly filtered.

Mission: Emissions

The Environmental Protection Agency (EPA) is not at the forefront of emissions ratings; California provides these benchmarks. Emissions efficiency of motor vehicles is measured at the tailpipe in particulate matter.

But there is also a secondary form of emissions: evaporative emissions that escape into the air in the form of fumes. This kind of emission usually occurs during fill-up at the gas station, but also takes place by way of venting from the fuel tank—vaporization of the fuel when the engine is running and heat soak after the car is parked. Depending on the vehicle, evaporative emissions can rival that of tailpipe emissions on hot days when the evaporation threshold is lowered.

California's Alphabet Soup

California's Air Resources Board (CARB) rates its emissions with catchy acronyms while the EPA's rating system uses a zero to ten scale in its "Guide To Green Cars" that allows direct comparisons between different model groups, i.e., compact cars and light trucks. Since California has more stringent emissions criteria and the car companies sell a great deal of cars there, the catchy acronyms get all the attention.

A List of all 2007 PZEV vehicles (non-hybrids)

According to the Golden State, ZEV or Zero Emission Vehicles have zero tailpipe emissions and are 98-percent cleaner than the average new model year vehicle. Only all-electric and fuel-cell vehicles can gain entrance into the ZEV category.

AT-PZEV or Advanced Technology Partial Zero Emission Vehicles meet SULEV (see below) tailpipe emission standards, carry a 15-year/150,000-mile warranty and have zero evaporative emissions. The Advanced Technology part of the term refers to components such as gas-electric hybrids or compressed natural gas vehicles, but not plain gasoline-powered vehicles.

The best a gasoline-powered car can aspire to is a PZEV or Partial Zero Emission Vehicles rating. Like AT-PZEVs these vehicles also meet SULEV tailpipe emission standards, have a 15-year/150,000-mile warranty and have zero evaporative emissions.

The difference between AT-PZEV and PZEV is PZEVs have no electric or other hybrid drive system. Many PZEV vehicles are sold in the states of California, Massachusetts, New York, Vermont and Maine as standard and required equipment and may be available as an option in bordering states.

SULEV or Super Ultra Low Emission Vehicles operate 90-percent cleaner than the average new model year vehicle. The difference between SULEV and PZEV ratings is the lack of evaporative emissions and warranty requirements.

ULEV or Ultra Low Emission Vehicles are 50-percent cleaner than the average new model year vehicle.

The last of these alphabetical tongue twisters is LEV or Low Emission Vehicles, which represent the lowest emissions standard for all new cars sold in California. Think of it as extra credit for being significantly cleaner than the EPA minimum.

The EPA's new scale shows two points of measurement; an air pollution rating and a greenhouse gas rating. Vehicles in the PZEV category mostly score 9.5 with a few 9s. The same make and model car in below-PZEV trim that are sold in states other than California, Massachusetts, New York, Vermont and Maine score 8s and 9s.

Fuel Economy

The second environmental concern for the new-car buyer is fuel economy. The benefits of good fuel economy are the use of less gasoline and saving all the resources that go into creating said gasoline. The owner also pays less money for fuel over the lifetime of the car. Fuel mileage is where the biggest difference between hybrid and gasoline-powered offerings arises.

However, with wildly fluctuating gas prices it can be difficult to put a real price tag on the savings. Since hybrids run on electricity more in the city and gasoline-powered cars are less efficient in slow-and-go city traffic, hybrids show the greatest advantage when city MPG is compared.

By the Numbers

Looking at the vehicle comparison, a significant trend jumps into the light—overall value. Cost-wise the average of the top three hybrids checks in at $23,658. Working the same equations with the top three gas-powered cars nets a bottom line of $13,101. The difference of $10,557 really wallops the wallet. (It should be noted that all prices are for the base model vehicle with no optional equipment added.)

So whether mileage or emissions output is the driving force behind the purchase decision the great divide tops $10,000.

From a fuel efficiency standpoint the Toyota Yaris is the standout because it delivers the best city MPG, 40 MPG on the highway (one MPG off the best score), ULEV emissions performance and does it with the lowest price on the road, $11,150.

Focusing in on emissions as the deciding factor, the Ford Focus moves to the top of the chart. It combines a SULEV engine with zero evaporative emissions and delivers 27/37 mileage, the best of the PZEVs, and does so at just over $14,000.

Hybrids Ranked By MPG

Vehicle City/Hwy MPG CARB/EPA Emissions MSRP
Prius 60 / 51 AT-PZEV/9.5 $22,175
Civic Hybrid 49 / 51 AT-PZEV/9.5 $22,600
Camry Hybrid 40 / 38 AT-PZEV/9.5 $26,200
Accord Hybrid 28 / 35 AT-PZEV/9.5 $31,090

Gasoline Ranked By MPG

Vehicle City/Hwy CARB/EPA Emissions Base MSRP
Toyota Corolla 32 / 41 ULEV/7 $14,305
Toyota Yaris 34 / 40 ULEV/7 $11,150
Honda Fit 33 / 38 LEV/6 $13,850
Ford Focus 27 / 37 PZEV/9.5 $14,130
Hyundai Elantra 28 / 36 PZEV/9.5 $13,395
Mazda Mazda3 28 / 35 PZEV/9.5 $13,795

The Toyota Prius puts up the best numbers because there are far less compromises in a vehicle designed from conception as a hybrid than in an existing platform that is converted into a hybrid. In some ways examining the gasoline and hybrid versions of the same car under the same microscope better frames the hybrid/gas proposition.

Head-To-Head Gas Vs. Hybrid

Vehicle City/Hwy MPG Emissions Rating MSRP
Accord Hybrid 28 / 35 AT-PZEV/9.5 $31,090
Accord (Gas) 26 / 34 PZEV/9.5 $18,625
Difference -2 / -1 Equal -$12,465

Accord and Accord Hybrid are equal in emissions and the one and two-MPG improvements cost a staggering $12,465.

Vehicle City/Hwy MPG Emissions Rating MSRP
Camry Hybrid 40 / 38 AT-PZEV/9.5 $26,200
Camry (Gas) 24 / 34 PZEV/9.5 $18,470
Difference -16 / -4 Equal -$7,730

Here we see the big advantage hybrids have in the city, 16 MPG more than the non-hybrid Camry. Those with freeway-dominated commutes will only see a 4 MPG bump. Again emissions is a wash as both vehicles are at the top of the scale. The price difference is $7,730.

Vehicle City/Hwy MPG Emissions Rating MSRP
Civic Hybrid 49 / 51 AT-PZEV/9.5 $22,600
Civic 30 / 40 ULEV/7 $14,810
Difference -19 / -11 Less -$7,790

The Honda Civic gas-versus-hybrid comparison shows the biggest gap in fuel efficiency and emissions. A PZEV rating is better than 90 percent of all cars while a ULEV rating beats only 50 percent. The price difference is $7,790.

The Bottom Line

Gasoline-burning PZEV cars are a cost-effective way to drive clean. How clean? On a smoggy day, or even a not-so-smoggy day, in downtown Los Angeles the emissions coming from a PZEV tailpipe will be cleaner than the air outside. Further, grilling a hamburger on the BBQ would produce more hydrocarbon emissions than a PZEV would on a three-hour trip (180 miles). In fact, PZEVs can burn cleaner than some hybrids when the hybrids' gasoline engine does not meet SULEV standards.

The most prolific PZEV is the Ford Focus with more than 100,000 of the DURATEC 20E-powered cars on the road since 2003. Ford recently began badging PZEV Focuses with a Green Leaf Highway emblem to enhance awareness because, according to Ford, many owners may not realize the environmental significance of their car.

The Catch

Geography can be conspiring against eco-conscious buyers. The PZEV's limited availability is not a result of sales volume, marketing or any other political force; it's all about fuel quality. The reformulated fuel available in what's called the California Emission States—California, Massachusetts, New York, Vermont and Maine—make PZEV possible. Take a PZEV to Kansas and the change in fuel quality will knock down its emissions performance. Many PZEVs like the Ford Focus may be available in states bordering the California Emission States but in the case of Ford the 130-hp DURATEC 20E engine is a no-cost option.

How Green

For those living on the right side of the tracks the availability of gasoline cars that deliver PZEV emissions performance and outstanding fuel economy make living a green life much more affordable compared to going hybrid. Those without PZEV can still get significant emissions performance, competitive mileage and go easy on the environment while reaping 5-figure cost savings. The key is to be well informed and know what you want before waltzing into the local dealership, be it down the street or in cyber space.

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