Can I use one ground as a reference for multiple inputs?

Thanks for the input.

The sending units on the engine are shown as the boxes with the ohm readings. They are only one wire, and carry no power that I know of, the sensor grounds through the threads onto the engine block. They change resistance with temperature/pressure. This is a project I could really use, and I am hoping to give it a try. There aren't any projects I want to do that AREN'T automotive related in some way (I'm a car guy) so I guess dealing with the noisy electrical environment is something I might as well start dealing with now, haha.

This is a snapshot of the manual from Auto Meter.