ref insurance, I used to be a fitter and run the South Wales RS club so I have a traders policy for me and the wife, and yes the A8 runs on LPG, normally £67 of fuel will go 300 miles, but £15 LPG will go 250 miles (nice) and it doesn't matter how you drive on LPG still get same fuel consumption even with aircon on.
Only thing I notice is slight loss of power.