[Piwoslaw]

I like to keep an eye on coolant temperature, mostly b/c of the grille block, but also b/c it gives an idea of how much work the engine had to do in a short time.
Next is fuel per hour - shows the load on the engine independent of the speed.
Total fuel used per trip - more important than average fe is how much fuel I actually used. This is the value I work on reducing.
The fourth slot changes - sometimes it's rpm, sometimes speed (both are more accurate than my dashboard dials), sometimes I'll fool around with something else.