That is exactly like the one I had. I really liked being able to set the cruise to the desired speed and it took you to that speed.
I don't think MB uses any kink of governor control except for max rpm. My 602 acts just like a gas engine as far as power goes. It will slow down going up hill and speed up going down hills. (Maybe it is broke.) So it seems that rack position could be used as an indication of fuel usage, but I don't know about boost. Does boost make the rack move to put more fuel in? I don't know.
For speed and rpm you can just use the current systems on the car and make signal buffers to get the voltage levels you want )(0 - 5 V probably).
If you deside to use the current temp,oil,fuel sensors let me know and I can tell you the problems I had trying to get accurate readings from them and how I did it.

Paul

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84 500 SEL (307,xxx miles)