tell me, in the days of microprocessor-controlled engine timing....

you are a car rental company. you rent vehicles that use regular. you rent vehicles that use premium.

how do you fuel your fleet? regular across the board and let the engine control module adjust the timing accordingly. or do you fuel selectively based on the vehicle manufacturers recommendations?

i ask this because hertz rents the majority of its vehicles that are intended for 87 octane, but rents some in its premium collection that are supposed to be fueled with 93 octane. but i have concluded that all are fueled with 87 octane gasoline.

am i right? am i wrong?