Five.O yah forgot fuel pressure! To me fuel pressure, oil pressure, and coolant temp are the three best choices! everything else is fluff
Something to make your girlfriend get giddy about and you to take your eyes off the road and smack into the tail of another car as you accelerate and watch everything move through their sweeps. Oil temp gauges tend to read about 30-40 degrees lower I believe relavent to the temp at the bearings? So their usefulness isn't all that.