Just spotted the ideal motor for you on UKRM:
In case anyone here has a need before I go advertising it locally. It's in Belfast. Sweet condition inside/out and the engine and 'bay are spotless.
Volvo S40 2.0L XS Auto Met green
1999
80somethingK miles CD unit
New OEM heavy duty springs and spax gas dampers F&R with tow bar and electrics Just had £700 major service, cam belt, discs & pads all round
4 new tyres with OEM alloys refurb'd New gell battery
LPG conversion just refurb'd with new filler valve and 55L spare wheel wheel tank
Around 30mpg on petrol with me driving. 26ish on gas.
£3000
'Hog
I've seen said car, and it was very tidy - also happens to be owned by en ex-BMW technician who isn't short of a quid or two to spend on maintenance.
LPG would suit your miserly attitude to fuel ;-)