You have the following:
- MPG (average)
- MPG (instant)
- Temperature
- Clock
- Journey time
- Range
The above (apart from the clock, temperature and range obviously) reset after something like 90 minutes.
If you press and let go on the reset button you get the secondary readouts - indicated by a little 2 next to the MPG (average) and Journey time - these do not reset unless they reach a certain threshold on time or mileage or if the battery is disconnected. A quick press on the reset button again will take you back to the original display - indicated by a little 1 in the same places described above.
Holding the reset button for just over a couple of seconds will perform a manual reset of either set of readouts.