There no advantage to gas,
My dad was going to buy a 4.8 x5 and convert it but gas just is not good enough for it yet.
Disadvantages are, you loose power, fuel cell has to be in the boot so you loose space, it runs hotter so possible to do engine damage
Dads mate had a range rover and had it converterd, had 2 engines in the space of 2 years, it just cracked blocks and constantly boiled up.
Its alot of money for what it is and really dont have any advantages apart from it wont make the hole in the ozone layer a bit bigger lol.
Me and my dad worked it out there is no advantage in fuel saving either, because you loose the power its burning twice as quick. so you may fill your tank up for £15 or something silly but it will only last half the time petrol did.
If you did gamble and you were lucky would you do enough miles for the time you keep the car for it to pay off? Even tho it burns twice as quick as petrol there is no fuel saving just tax saving from the way we looked at it
Maybe someone could correct me from their experience but my dad spoke to servral salesmen at BMW and toyota (my dad is a 4x4 fan
) So he loves Fuel guzzlers LOL