One problem related to cruise control has been reported for the 2009 Hyundai Elantra. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2009 Hyundai Elantra based on all problems reported for the 2009 Elantra.
Traveling on interstate, using cruise control (as I had the day previously and for approx 150 miles this day) attempted to stop vehicle due to vehicles slowing down in front of me. Could not get out of cruise control - in fact, the vehicle accelerated -- and brakes did not work. Fortunately, I was in the right lane and was able to exit the highway without hitting the guardrail (approx. 20 feet away when I left the highway), traveled at a high rate of speed down a slight embankment and into a field, where fortunately there were no obstacles, and was able to stop the vehicle approx. 500 feet from leaving the highway. The engine was still running, now at a normal rate. I attempted to return to the interstate but was not successful due to the embankment. I drove through my previous tracks in the field and was able to get onto a nearby exit ramp. The vehicle functioned normally after that. Please note, this vehicle has a manual transmission. I did not attempt to engage the clutch to put the transmission in neutral because I had both hands on the steering wheel trying to maneuver through the field, which was quite green, actively growing, and approximately 15 inches high. The crop scraped the underside of the vehicle, which is now in the shop waiting to have the new part replaced. The mechanic will check for damage on the underside. I am not sure if the vehicle stopped b/c the brakes finally kicked in or the vegetative growth slowed me down.