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Keep in mind that there's a limitation regarding instrumentation that directly measures fuel injection pulses to get fuel consumption data.
They absolutely depend on the assumption that there are no variations in the differential pressure between the fuel rail and the intake manifold. With the vast majority of cars, this is a valid assumption. Late model Chrysler products, tho? Not so much.
Most cars either have a fuel pressure regulator that is modulated by intake manifold vacuum, or their engine computers perform fuel pressure adjustments by varying the fuel pump. In either case, the fuel pressure is varyed such that there's always a constant pressure differential between the fuel rail and the intake manifold, typically 43.5 psig.
Late model Chrysler engine computers estimate the pressure differential between the fuel rail that is fixed to a constant pressure at the tank-mounted fuel regulator, and the varying pressure in the intake manifold. The computers then adjust the injector pulse widths by that estimation. It's elegant for the car, but it will absolutely throw off any fuel consumption calculations unless you know how to compensate.
My MPGuino code can do this compensation, and I ran it for many years on my Dodge Magnum.
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