Hyundai Repair: warranty work, hyundai alantra, poor gas mileage

Question
I have a 2003 Hyundai Alantra with approximately 40,000 miles. Currently it has a dead battery but I am getting that taken care of today. My question is if I get a regular mechanic - non Hyundai - to work on the car, does it void the Hyundai Warranty? My problems are: possible slow leak in radiator - car sometimes gets hot; slight "slip" when you take off; poor gas mileage.

Answer
No, it will not void your warranty.  The warranty will continue to cover what it says it will cover, defects in factory materials and workmanship.  What your factory warranty won't cover will be the work your other mechanic does, the parts he used, or any damage resulting from that work.  But your other mechanic should be willing to give you a warranty covering his parts and labor.