One problem related to engine noise has been reported for the 2018 Hyundai Elantra. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2018 Hyundai Elantra based on all problems reported for the 2018 Elantra.
Engine noise became very loud over several days; took to dealership which told me a weld in the exhaust piping system had failed and that the exhaust pipe had broken open. They said it was not safe to drive because of potential for exhaust coming into cabin, ordered the part and gave me a loaner, on 10/2, saying the earliest I could reasonably expect to have my car back would be 10/18.