Do I need to re-calibrate my toyota corolla if I am living in a city 9500 feet above sea level?

When on the steep parts, up or down, Kick it out of Overdrive. Should show OD OFF in orange on dash. Even drop it to "2" but not at high speed, under say about 40 mph and let your engine run fast. Won't hurt anything and will save brakes downhill and not lug uphill. Those guys Tom and tennisshoes are right, your ECU 'knows' what to do to compensate. Don't be afraid to put your foot it it, it has VVTi (Variable Valve Timing intelligent) Uses engine oil pressure to adjust the camshaft position and that does not kick in until about 4000 rpm The valves will adjust to give you more power. But a 2015, if brand new don't run it really really high rpms until it has a couple thousand miles. Then after break-in you will have noticeably more power. But like I say, don't be afraid to use that system, it's there for a reason, put the pedal to the metal up hill. I'm not saying drive it at 6200 rpms all the time which is the red-line, for both the 1.8L or 2.4L. The rarefied air will cause the ECU to 'tell' injectors to release a little less fuel to keep the optimum, hence the 3% per 1000 ft loss Tom was talking about. Now I don't know if you travel from a much lower elevation to 9500' and back often, or just mean you remain up that high. My little essay here is about going up and down from low to that altitude. Bottom line, the VVTi works. I's an ingenious system that adjusts the valve timing, lift, and lift duration. But you have to allow your engine to use it -- with throttle. And in case you were wondering, regular gas is fine. No need to use 89 or 91 octane. Won't give you more power. BUT BUY name brand gas, no cheap convenience store junk. Today's gas is already garbage at best, and cheap means it does not have the detergents your car needs Drive safe my friend.

Remember do not use anything but 0W20 motor oil. That's very important. You engine was not 'designed for the oil' so to speak, but the design result demands the thin oil, for the VVTi for one, the timing chain needs a thin oil and the newer 1.8L engines, although the same cubic inches, or cc's, have a bigger piston and a shorter stroke, resulting in a slower piston speed at same rpm as pre-2009. Now, This is a list of gasoline retailers approved by BMW, Honda, Mercedes, GM, Ford,Toyota- http://www.toptiergas.com/retailers.html