Have a 2011 Elantra GLS for 6 months now. Very, Very, Verify, disappointed with MPG not even close to advertised 40 mpg. I drive 80% highway, the best I got was 30mpg @ about 70-75mph. In the city I get 18-19mpg. VERY disappointing about the misleading advertising. Will NOT recommend this to anyone.
There are many factors that reduce fuel efficiency.
Driving at 70-75 mph with A/C on is one of them.
Your driving habits must be terrible.
Go to cleanmpg.com and read up on how to improve your driving habits.
Popular Mechanics did real driving tests and not lab tests like the EPA and exceeded the EPA numbers.