> And fuel injected vehicles run fine (because they can adjust for the altitude on the fly) A bit of pedantry: modern automotive electronic fuel injection wit

> And fuel injected vehicles run fine (because they can adjust for the altitude on the fly) A bit of pedantry: modern automotive electronic fuel injection with exhaust oxygen sensors adjust much better to altitude, but the first aircraft and automotive fuel injection systems used the Venturi effect acting on a spring-loaded diaphragm to estimate mass flow rate, and simple mechanical computer to adjust fuel flow needle valves. Early aircraft mechanical fuel injection systems contained an altitude-compensating aneroid, but I doubt early automotive models did. Many small recreational aircraft still use altitude-compensating carburetors that contain aneroids that act on needle valves to compensate for altitude. Even today, the oxygen sensor is a relatively expensive part, and it's possible that early electronic automotive fuel injectors didn't measure and compensate for oxygen concentration in the exhaust. So, an old automobile retrofitted with an aircraft altitude-compensating carburetor may very well compensate for altitude better than an early fuel injected automobile. Though, I assume only a handful of cars have ever been retrofitted with altitude-compensating carburetors.