I'm not sure if this has been asked before but I'm wondering if there is more than just the rev and coolant temp gauges. Is there a way of getting oil temp (and maybe pressure too) on the PID?

Not seen it

Would be useful but not seen anyone do it. Maybe you could be the first?! 

A German software engineer over on the SEAT forums found a way of customising the PID software for the Ibiza Cupra. It was a few years ago now. I asked for some help/info regarding customising the Up!/Mii/Citigo PID but heard nothing back. Bit of a shame as I have been a software engineer for over 30 years now and have some Win CE development experience.

I seem to remember that the up had some extra gauges on it's maps and more software. Im not entirely sure though. Not sure where I'd start with custom software.

It appears that the Volkswagen software only has an eco driving assistant, not extra gauges. Due to having no idea how I would get extra gauges on the PID I will instead be opting for a set of VDOs from an Audi 80. Anyone got a diagram for locations of oil temp and/or pressure sensors?

You can indeed change which gauges are shown via the options on the gauges display.  Don't think there's much more choice though. 

Just checked ours today and the three different options are.....

 

Rev counter

Water temperature

Outside temperature

 

 

Ours is set for water temp and outside temp. 

Some useful information obtained then. I'll probably go about using some physical gauges for oil temp and pressure. I might put one in for battery voltage