Originally shared via the forum, this is a pretty neat hack found on how to turn your radio display on your new Honda City (year 2009 onward) into a speedometer, like on the current generation of Honda Civic. However, there is a downside to this, you can’t listen to radio when this is active.
First, switch off the radio.
Next, hold down both the up and down arrow on the radio controls.
While still holding down on the up/down arrow, switch on your radio.
You will notice that the display has the word DIAG on it. Press on the right arrow to initiate the speedometer mode.
And you’re done!