https://www.sportsubaru.com/subaru-pzev-explained.htm
The Subaru PZEV (Partial Zero Emission Vehicle) is the affordable, no-compromise, eco-friendly alternative. Although the Subaru PZEV runs on regular unleaded fuel, it offers significant smog-reducing environmental benefits and delivers equal performance compared to non-PZEV cars or SUVs, including hybrids, diesels and alternative fuel vehicles.
A PZEV is classified as the cleanest-running gasoline-powered car on the market and was developed to meet the air quality standards of California, the most stringent in North America. A PZEV must meet the Super Ultra Low Emissions Vehicle (SULEV) tailpipe standard and have zero evaporative emissions
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They don’t have great MPG numbers, but do burn very clean... part of the mileage issue is the all wheel drive ability.
A big selling point is that the US factory produces no waste to be landfilled.