In calif.,I was climbing the grapevine [5]south, to get back to L.A. the noise was awful, loud grinding chains in the engine area. i thought it would blow up! i tried other gears, but it just got louder. the car overheated almost to the danger zone.it did make it up the 4000 ft. hill. but now im scared to drive it up again.the dealer said bring it in . i am not looking forward to more repairs. am i driving it correctly? do i need to change gears?its automatic. ive had many cheap cars that made it up the hill fine. im so disappointed.this car does need a new cat. converter. will be up for sale as soon as its done. i hate this car.no starting power when first accelerating, all wheel drive is crap. have heard engine gets sludge problems, tranny often fails after 100,000 miles. will never buy lexus again.