[lowglider]

If your iS is in good condition (will not need costly repairs in the near future) then I`m for LPG all the way. Because you get to keep all the fun while driving a lot cheaper, not to mention that LPG is friendlier to the enviroment and also to the engine, you can prolong oil changes with it.

Getting another used car is always a lottery and diesels under £1000 are prone to rattle, leak, smoke, understeer and be a pain in the arse way more than a 318iS can ever be.

As from personal experience, years ago I went from an E34 to a 1.8Td Mondeo and although the Mondeo was 6 years younger, driving it was always a sob story compared to the joys of the BMW, not to even start mentioning the build quality difference and repair nightmares.