One problem related to catalytic convertor has been reported for the 1999 Hyundai Elantra. The most recently reported issues are listed below.
In-shop for transmission 3 times (on 3rd trans); paint peeling on bumper (dealer refusted to paint);clear coat cracked and bubbled on spoiler & side mirror (dealer repainted); noticed a/c didn't work right after purchase; check engine light on (reason for replacing engine coil, etc. And converter); interior driver's door handle broke; dealer always fights getting us a loaner/rental car (but we have to have one since its our only car now!); always in shop an extensive amount of time except when they are paying for us a rental; manufacturer contacted by phone in may 2001, but offered no help.