Are you referring to the new Disco Sport? That does have gas/diesel options in the UK, although over 90% are diesel according to what's available on Autotrader. EDIT: Nope actually according to Land Rover, it's diesel only here. You were right.
Our fuel is different to that in North America, it burns cleaner and more efficiently, plus as it's about 300% more expensive, most people are more keen to drive carefully and save it that to play "fast and furious" at every intersection like they do in the US
Our emission standards focus a lot on C02 emissions, this is directly linked to the amount of fuel burned, there are more efficient versions of engines here, Bluetech, Bluemotion, Ecotech, Puremotion etc that save a further 10-20% V's the other engines that may only be available in the US.
I've bought up the engine issue before, L3, H4 etc, it should be classed as engine size rather than layout, and gas/diesel/other fuels too. Most people know the size of their engine. Last time i checked, the VW Passat had 52 different engines listed on fuelly, there