just to add, i have a vertical donut tank in the spare wheel well, and have NEVER been able to empty it in less than 180miles, and i was trying hard in the early days of the install to find out the worst possible range.
Driving at normal, above legal, motorway speeds gives about 200. 230 is possible, more if you really want to drive purely with economy in mind, i dont have the patience for that though. I cant help with a town figure as my commute is 90% motorway. For me donut in spare wheel well was the only option as i need the through space to drop the rear seats down.
Having said that, the fact i have 5 lpg stations in Reading was definately a deciding factor. In affect, you need to reduce your affective tank range by the distance needed to drive to your nearest lpg station if its in the wrong direction to your regular journey. But if there is an outlet near your most regular route, why worry? Something to consider when making your decission.....?
Tbh, a boot full of "stuff" is no reason to fit a donut. Take the stuff out and fit a 100litre it seems to me, it will save you money, stuff will just cost you money to lug about. A doubly expensive way to drive perhaps? (Unless the "stuff" is actually needed of course :-) )
New Kit over second hand by the way, fitting new is challenge enough.