2001 Nissan Sentra CA

When "environment" is placed in context with cars, thoughts often turn to alternative-fuel vehicles of one type or another. Hybrids such as the electric/gas Honda Insight or Toyota Prius carry the highest profile in the enviro arena these days, garnering more attention than battery-powered cars like the GM EV1.


Things are changing. Enter the Nissan Sentra CA, a decidedly mainstream sedan that runs on that standard un-alternative fuel, gasoline. The trick is that this car goes about its job so efficiently that it qualifies as a Super Ultra Low Emission Vehicle (SULEV) in California, the state where cars have long been held to higher standards of environmental performance.

Stylish at the rear with its high deck and overall sporty profile, this super-ultra-low emission Sentra is identified with a small "CA" emblem inboard of the passenger's side taillamp.

That a gasoline-fueled car achieved this distinction is significant. The SULEV designation not only requires extremely low tailpipe emissions, but zero evaporative emissions as well. This is straightforward in a compressed natural-gas vehicle with a closed fuel system, but a very real challenge in gasoline-fueled vehicles that traditionally suffer evaporative emissions as a matter of course.


Bringing tailpipe emissions downward is typically a function of more sophisticated electronic combustion control, greater use of precious metals in one or more catalytic converters, and perhaps a catalyst located closer to the engine so it heats up faster to begin treating exhaust more rapidly. No magic here—just more elegant engineering than the norm. In the case of the Sentra CA, Nissan went the extra mile by also including double-wall exhaust manifolds, hydrocarbon trap catalysts, and a non-return fuel system. An electronically controlled swirl-control valve is also used to reduce hydrocarbon emissions during startup.


The Sentra CA radiator features an Engelhard PremAir catalyst coating as a final emissions-fighting measure. This innovation, field-tested by Ford in the mid-1990s and ultimately incorporated on some Volvo models by the end of the decade, uses a catalyst coating to convert ozone molecules into oxygen. In effect, a Sentra CA scrubs ozone-laden air as it drives, theoretically leaving the world a cleaner place as it goes.