Toyota Avanza 1.3L gasoline engine is a good choice and it can be equipped with a LPG kit (with factory warranty intact) from a Toyota accredited installer. So although gasoline might be expensive, LPG is still cheaper and does makes sense if you consider the fuel cost savings (IF your van will be doing a lot of kilometers a week).
Above quote is from ghost hunter from another thread.

WHo are the Toyota accredited installers? If my Avanza's FC does not improve, might be worth it to convert.