That seems amazing that you can get so good consumption for your LS400. I own a 95 LS400 and my full tank can only give me around 290 km, but I live on a hill; i.e. everyday I travel up and down hill, that would make quite a bit of difference. But 400 miles is amazing, I wonder what do I need to do to get better consumption as here petrol costs around 90p per litre.
Also does anyone have any experience in using those fuelsavers- Powermax or Fuelsaver device which cramps on the fuel supply line and uses magnetic field to reduce fuel consumption ? Are they of any use and is it easy to install by amateur- where is the fuel line ? I'd appreciate any help please.