See also:

Check Spark Plugs and Ignition System
Inspect your spark plugs and replace them if necessary. Also check all ignition wiring and components to be sure they are not cracked, worn or damaged in any way. ...

Vapor Hose and Fuel Filler Cap
The vapor hose and fuel filler cap should be inspected at those intervals specified in the maintenance schedule. Make sure that a new vapor hose or fuel filler cap is correctly replaced. ...

40 MPG POWERTRAIN
Under the hood, the Hyundai Elantra is powered by an all-new 1.8-liter Nu four-cylinder engine with 148 horsepower and 131 lb-ft of torque (145 horsepower and 130 lb-ft of torque for Elantra PZEV) ...