The new Hyundai Elantra carries an EPA highway fuel economy rating of 40 mpg thanks to lots of careful engineering in its design.
Chevy has a special version of the Cruze called Eco that sets a new benchmark rating of 42 mpg on the highway, though to get that number the driver must shift their own gears with a six-speed manual transmission. The Cruze is available with an automatic, but mileage drops below 40.
The Cruze Eco is a hyper-miler's dream with many special fuel-saving tricks. It sits a bit lower for reduced drag and even has panels underneath to further let the air slip by. Up front, the grill is different and the lower section closes at highway speeds to improve streamlining. Special lightweight wheels and low rolling-resistance tires further increase efficiency and a dashboard light suggests when it's ideal to shift up to the next gear.
Hyundai is boasting that their Elantra gets 40 mpg without asterisks. Every version of the car is rated at 40 mpg on the highway.
But there does need to be an asterisk to these figures. Highway mileage ratings are done under idealized conditions. Highway travel in Southern California is hardly ever ideal. Mandated fuel blends also cause a small loss in mileage.
Nevertheless, with gas prices so high, even a chance at 40 or more miles per gallon looks pretty good these days.
One more thing: both cars are roomy for being this fuel efficient. In terms of safety, the Elantra has six air bags. The Cruze has 10 air bags.