Fuel loss and cat damage.

By my calculations, that works out at about 17 mpg. The 'official' fuel economy figures for a 1997 V8i Discovery [see link below] suggest around 19 mpg, so I don't think you're far off at 17. Welcome to the world of V8 engines...

--> Greg

Doesn't sound too awful. Ignore the gauge - mine is hopeless, though better than a lot of other cars. You might expect the 4.6 to be a bit more efficient than a 3.9, but then you have a lot of other crap (sorry, essential off road kit) bolted on. Mine does 18mpg on petrol, a little less on gas, on standard wheels and no essential off-road kit fitted.

As for cats, well I paid £600 for mine replacing with non-genuine ones and I haven't noticed any major difference over OEM. If they are rattling I'd check the fittings haven't worked loose - mine did.

If you think you have a leak, fill it to the brim and leave it a day or too. See if you can get any more in after that. A leak is usually obvious if it's from the tank end - in the engine bay I guess it could just vaporise without being detectable.

Oh, meant to say...

I get 300 miles comfortably on a full tank before the yellow light really starts to worry me. I have had 320 miles on several occasions, and once I managed 340 miles in the depths of Lincolnshire, which apparently is served by only 3 petrol stations, 2 of which are closed down. It was a brown trouser moment really, due to the 8 and a half month pregnant missus getting more than slightly stressed and we all know what that can bring on!