See also:

Reporting safety defects (U.S.A only)
If you believe that your vehicle has a defect which could cause a crash or could cause injury or death, you should immediately inform the National Highway Traffic Safety Administration (NHTSA) in ...

Valve clearance
Inspect excessive valve noise and/or engine vibration and adjust if necessary. An authorized HYUNDAI dealer should perform the operation. ...

Use of MTBE
HYUNDAI recommends avoiding fuels containing MTBE (Methyl Tertiary Butyl Ether) over 15.0% vol. (Oxygen Content 2.7% weight) in your vehicle. Fuel containing MTBE over 15.0% vol. (Oxygen Content 2. ...