The number 1 is the trip function of the computer, all details in this function will reset to zero when the ignition has been turned off for 2 hours or more. If you press the reset button on the lower edge of the wiper stalk the display will change and show a red 2 which is the accumulative function of the computer and as it's name implies it will keep a running total of miles travelled average speed, average mpg until such time as you want to reset the computer yourself.
By pressing the reset button briefly the display will change: Trip 1, Accumulative 2 , Environmental, Nav display (if fitted) and digital speed readout.
You will also see the 1 or 2 below the speed if you have the digital speed setting on the DIS and by using the rocker switch on the end of the wiper stalk you can scroll through the computer readouts.
It is! Trying to remember where everything once was! My Eco mode is constantly set to off, I have to manually switch it on now. Has this setting been messed about with while the battery was disconnected? How do I switch it on in the settings?
If you do not have Tech Pack (Nav) have a look in CAR settings on the MMI, scroll to instrument cluster> On Board Computer1 or 2, select 2 and turn on required information. You should also be able to turn on Eco settings here as well IIRC. This function is not available on Tech Pack vehicles.
By Eco function do you mean the economy tips which appear within the Efficiency programme? If so these are only displayed if the fuel consumption increases in certain circumstances and are displayed automatically and will only appear if the Efficiency programme is selected. They also automatically disappear after a "while". To quote from the manual:
"The economy tips are not always displayed in every conceivable situation, but are deliberately spaced out over time". That may be why you are not seeing them!