I just unlocked a new (well its factory)secret on my car THE DIGITAL RPM GAUGE where it shows trip/total km.
Well the steps are:
NOT RECOMMENDED WHILE DRIVING DIAGNOSTIC PURPOSES ONLY!!!

ignition OFF
press and HOLD the reset button on LEFT of cluster
ignition ON
wait 3 Seconds
Ignition OFF
And Turn back ON quickly DO NOT START ENGINE
And you should see 1 and then 4 numbers mine is (3764) yours could be different.
Then press through and you will have 8 options to choose from .
(not sure what they all are )
the one we want is NO 7 .
so when you get to 6 press and hold button and it will move to 7 .and then 0 which is your rpm .
and your DONE start engine and enjoy .
NOTE : when you turn off the ignition after starting the car the rpm resets so you have to do the steps again . oh and you can have you cluster lights ON while doing the steps. ENJOY