The consumer watchdog Ecology Center’s HealthyStuff.org, a product test results website, points out that there is more to green vehicles than fuel economy. That new-car smell can include a toxic mix of chemicals carried over from the manufacturing of seats, steering wheels, dashboards and armrests. The group’s fourth annual report on more than 200 model year 2011 and 2012 vehicles gave the Honda Civic and CR-Z and the Toyota Prius top marks for the least interior pollution, while the Kia Soul, Chrysler 200 SC and Mitsubishi Outlander ranked as the worst.

The researchers tested for toxic heavy metals such as lead and mercury, and cancer-causing chemicals like benzene and brominated flame retardants. “Automobiles function as chemical reactors, creating one of the most hazardous environments we spend time in,” says Jeff Gearhart, research director of the Ann Arbor, Michigan-based nonprofit.

No mandatory testing or regulation of the chemicals used in vehicle manufacturing exists, so consumers face a lack of helpful information. The use of some chemicals has voluntarily declined since 2006, but many cars continue to contain chemical levels that consumer advocates consider unsafe. The biggest decrease has been in the use of plastics made with the highly toxic polyvinyl chloride (PVC), as well as bromine, chromium leather dyes and lead.

View the full list of cars in the report at Tinyurl.com/carsrated.