In stock car racing, there's an old adage: If you ain't cheatin', you ain't tryin'. You could say the same sometimes for auto makers up against stricter environmental rules.
If you're driving a diesel-powered four-cylinder Volkswagen, you're stuck with a fun-to-drive machine that's belching unhealthy pollutants from its tailpipe.
Where does a practical car like the Toyota Prius go to reinvent itself? The same place many people go to let loose and have fun: Las Vegas.
The 2016 model year has plenty of workhorses, including new versions of the Toyota Tacoma and Nissan Titan pickups, Chevrolet Malibu and Kia Optima sedans and the Honda Civic small car.