If your MR2 is like most autos it uses an O2 sensor in the exhaust as part of a feedback loop to dynamically adjust mixture (timed injector pulses) via the ECU (engine control unit/computer).  It also uses a mass airflow sensor up front as part of that automatic mixture control process.  Thus in the automotive case, fuel pressure is not really critical (as long as it is in the appropriate range to cause atomization from the nozzle), since the ECU controls mixture via electrical fuel injector pulse timing (it also controls spark timing).  The whole system is actually quite sophisticated to enable maximizing, horsepower, durability, and economy, while also minimizing emissions, and it could easily adjust for 26,000ft and/or M60F, but it’s only practical due to spreading the development/testing cost over large auto production volumes.

 

The down side is if anything goes wrong, it can easily just stop.  My new Chevy Suburban was dead on the side of the road, when a $5 crank position sensor went south.  Luckily, it’s way too heavy to get off the ground in the first place {grin}.

 

Rick