averaged 22mpg on lpg 
It really does still make me question how viable LPG is now, if that's what you get on a run ( about the same as my 2.0 did )
I had an "enthusiastic" V6 run today, about 160 miles in total. I reset the CID before I moved away, and at the end of that mileage I had over 33mpg on the screen - and this is on a 3.0 V6 !
So - 22mpg at approx 56p per litre - or 33mpg at approx 1.10 per litre.
It would take quite some time to break even there - and all my miles are motorway these days.
Although I like LPG and I like installing it, I'm still not convinced about converting my latest 3.0 Estate, if I can get near 35/36mpg on a careful run :-/
methinks you are not comparing like-with-like 
Portsmouth - Swindon ... 80 + miles in a little over an hour is moving quite quickly ... so an "average" of 22 mpg (LPG) is IMHO pretty good. my guess is if he had taken 1 1/2 hours he'd probably get well over 30 mpg (LPG) and that is cheap motoring !!
LPG is 59 p/litre .. thats £2.68 gallon .. at 22 mpg thats 8.2 p/mile
Petrol is £1.15 /ltr thats £5.22 .. you got 33 mpg thats 15.82 p/mile
so worst case is .. TD saved 7.6 p/mile .. and if he'd gone a little slower would have saved even more !!
80 + miles @ 7.6 = saving over £6.00 just on the way home !!
LPG still works out far cheaper in pence /mile

I must agree to a large degree - my 2.0 would achieve near on 30mpg if I was very very careful on a run... on LPG...
which works out at 60mpg running cost wise - so better than 36mpg out of a 3.0.
At the moment though, (and I don't mean to sound pedantic here) - for what I would save, having free time is worth more to me - at this moment in time - than saving a possible 8 pence per mile

Fact is, every day I am so wrapped up in something Maria doesn't see enough of me - so I guess, the initial conversion is more tricky for me to do, than anything else.
I may well consider it when things settle in December - but as it stands, I am in no rush to convert
