I take this car up to big bear with a full car (6 people, the center front armrest comes up and has a seatbelt underneath) and it has never broken down on me once. The ride going there is completely smooth cruising at 80 mph, even though the Avalon's engine has more than enough power to go over that even with a full car. It has no trouble getting up those steep hills and is my car of choice when driving up to the mountains every season. It also survived a trip all the way to Sonora in Northern California from San Diego with a very steep mountain to climb at the end as well. Again, the car did not disappoint. Would highly recommend this car to anyone looking for an extremely robust vehicle.