Are Cars Still A Problem?

The report challenges claims by the American Automobile Manufacturers Association (AAMA) that modern cars are 90-96% cleaner than 1960s precontrol cars. It finds that real-world emissions are significantly higher than regulatory standards due to equipment malfunction and 'off-cycle' driving. Furthermore, a 2.7-fold increase in total vehicle miles traveled and a shift toward light trucks—which have less stringent standards—have offset per-vehicle gains. Consequently, while hydrocarbons decreased, nitrogen oxide emissions for the total passenger fleet actually increased by over 20% between 1965 and 1995. The author concludes that passenger vehicles remain a primary source of carbon monoxide and smog-forming pollutants, necessitating a shift toward intrinsically-clean vehicle technologies.

• Industry claims that modern cars are 90% to 96% cleaner than precontrol cars are overstated because they rely on emission standards rather than real-world emissions. A model year 1996 car's real-world emissions are estimated to be 4 times higher for carbon monoxide, 2 times higher for hydrocarbons, and 3 times higher for nitrogen oxides than the standards imply.
• For the entire US passenger vehicle fleet, total emissions reductions from 1965 to 1995 were modest or non-existent. Carbon monoxide emissions were reduced by only one-third, hydrocarbons by about two-thirds, and nitrogen oxide emissions increased by over one-fifth.
• The growth of the light truck fleet (including pickup trucks, minivans, and sport utilities) has significantly offset pollution reductions. Their market share rose from 15% in 1970 to 40% in 1995, and their share of smog-forming pollutants (hydrocarbons and nitrogen oxides combined) has doubled over 30 years.
• Increased vehicle usage has eroded per-vehicle emission gains; total miles driven by all US passenger vehicles increased 2.7 times between 1965 and 1995. Specifically, miles driven by light trucks increased 5.9 times, compared to 2.2 times for cars.
• Passenger vehicles remain a dominant source of air pollution in the US. In 1995, they were the largest single source of carbon monoxide and the second largest source of hydrocarbons and nitrogen oxides, accounting for 56%, 23%, and 24% of the national emissions inventory for those pollutants, respectively.

APA

Hwang, R. J. (1997). Are Cars Still A Problem? Union of Concerned Scientists. https://www.ucs.org/sites/default/files/2019-09/acfem4qn0.pdf

Chicago

Hwang, Roland J. Are Cars Still A Problem? Union of Concerned Scientists, 1997. https://www.ucs.org/sites/default/files/2019-09/acfem4qn0.pdf.

Wikipedia

{{cite report |last1=Hwang |first1=Roland J. |title=Are Cars Still A Problem? |publisher=Union of Concerned Scientists |date=December 1997 |url=https://www.ucs.org/sites/default/files/2019-09/acfem4qn0.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{hwang1997are, author = {Hwang, Roland J.}, title = {{Are Cars Still A Problem?}}, institution = {Union of Concerned Scientists}, year = {1997}, month = dec, url = {https://www.ucs.org/sites/default/files/2019-09/acfem4qn0.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }