2002 hyundai sonata

if the gas tank has a leak will it cause vehicle emissions to show up as not ready? thank you

Hyundai Sonata 2011

Burning to much gas. Burned 23 gallons to drive 36 miles what can be done to get better mileage.

1999 hyundai sonata gls v6

My cars runs rough at idle while in gear. It runs smooth when I put it in neutral or park. What should I check?