Good info, Simon, thanks.

I'm considering LPG, but there aren't too many filling stations close to me, and my daily journey is less than 3 miles, so I doubt I'll be able to switch to LPG on those trips. I just have to work out how much it will really save me.

Filled up in mine today (2.5 V6 2001 Aero tintop, bought 4 days ago)- I clocked 398km since first fill up and when filling the tank put in 45.75 litres to fill it up again.

Putting that into old money I seem to have got 24.88mpg, which I'm pretty pleased with as I was only expecting about 20mpg ...