[jcp123]

Small volume builders now have an exemption to many of the safety and smog laws. This is how you get new-build Superformance Ford GT40 replicas and the like.

Emissions testing is hardly uniform though. In Texas, for instance, only counties above a certain population (500k, I believe?) administer emissions testing. By contrast, California conducts emissions testing across the board, and to stricter standards than Federal mandates. I believe much of the Northeast has followed suit.

More to the point...4-cylinder doesn't necessarily equate to fuel economy. Nor is there a perfectly straight correlation with other factors such as engine displacement. Gearing, mechanical condition, driving style, etc. all affect the real-world fuel economy of a vehicle.