The dynamic range of the fuel injection feedback control loop is probably
a factor of 100 or so (pressure and injection time).  It's my
understanding that the two primary feedback signals are the AFM, which gives
the approximate point of operation within the dynamic range, and the O2
sensor, which provides a fine adjust within a very small percentage (1% or
so?) at the optimum point within the dynamic range.  It's difficult to
imagine a "manual closed loop"  configuration that would work better in a
Vanagon, and easy to imagine that any would work far worse.  Note that in
the straight and level airplane example the throttle is fixed and the load
is fixed, both of which are impractical when driving.

Cheers, Tom Neal '87
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Some key feedback loop variables to contend with:
open loop gain
closed loop gain
phase margin
dynamic range
slew rate
saturation performance
bang-bang or analog output  (Vanagon is bang-bang [digital])
time delays
sampling rates
crossover points
....is this more than we wanted to know about control systems yet?