Get the Range Rover 4.4 petrol and get it converted to LPG and you can run it on 50p per litre, which effectivley double the MPG. Makes it a lot cheaper to run than a diesel.
I had the 4,4 V8 Vogue SE, and it loved the LPG, I now have a Jag S-Type and that loves it also, the missus has a Hyundai Santa Fe on LPG, and We've had a Jeep Grand Cherokee, Merc E200, Land Rover Disco 4.0V8 all on LPG.
We started on LPG about 10 years ago when it was hard to find, now the LPG stations are all over the place like Asda's, Shell's, BP's, plus most camping gas places have filling stations, like Cheshire gas.
The missus goes to a place in Eccles that has a pre-pay card and she gets it for 43p per litre.
To have it converted can add from £800-£2000 to the price, but it will pay for itself in no time.
If you register your vehicle as running on alternative fuel you get a reduction in road tax.