mpg was running about 25-26mpg, for no reason its dropped to 18mpg?
any ideas?

What engine/year?

Might be an egr issue or a stuck brake. Are any of the wheels hotter than the others after a bit of a drive?

Mine does exactly the same in prolonged cold wet weather. Down to sub 18 mpg at the moment with short trips. Worth checking brakes and bearings as anything dragging causes rapid drop in mpg, also tyre pressures in this cold spell, any drop again hits mpg. TDV8 Java Black, Overfinch 22s

Fuel burning heater? My son pulled the fuse out on his FFRR as it was burning so much diesel.

3.0v6 2011

There's loads on this site about mpg but I would be concerned if my 3 litre v6 was only giving 25-26mpg as that's what I get from my older TDV8! True average for me over about 15000 miles is 25.3. Surely you should get more. And 18 is really worrying. Are we talking only short journeys here?

I'm seeing no change in mpg during the wet weather recently, and during the earlier cold spell I was using my remote for my fbh often without noticing any appreciable difference to mpg. So it's all a bit baffling. However it might be a good idea (phillh) to take out the fbh fuse to isolate that and see what you get in case it is running constantly. Robin
2008 Range Rover Sport TDV8
Gone:
Jaguar S-Type V8 4.2 Sport
MGZTT 190 2.5

what number fuse is the fbh? and engine fuse box or interior fuse box?

My car is a 2005 TDV6 and it is fuse no 28 (20 amps) in the engine fuse box.

Your car is later so it could be different. There is a sticker on the underside of the fuse-box cover showing the fuse numbers, its also in the owners manual.

thanks