BIG difference in aerodynamics though, even though the frontal areas are
similar the disco cuts a much cleaner line through the air, especially at
speed.
Badger.

Unless I am mistaken the Discovery is higher geared, and the aerodynamics
are different. But the major effect on mileage is driving technique plus
things like tyre type and pressure.
JD

I doubt it's genuine.  he might be a very careful drive and coast down every
hill and so forth, but I don't reckon you'd get 40 mpg otherwise.

I keep accurate records over more than a thousand miles to get fuel figures,
and I've never yet seen anything like that from the 300 TDi disco.

It does partly depend on use: if you did only longish journeys on flattish
roads at 50 mph, you might get 40 mpg.

The only way to get accurate fuel figures is to start with a full tank,
drive, then fill the tank again and work out the economy based on the miles
covered.  You can and should for better accuracy extend this by keeping note
of all fuel put in and then finishing up with a full tank, this will reduce
below a statistical level the errors in tank fullness which are inevitable.
currently I'm doing this for the latest minibus, so far I've covered 1462
miles on 48.43 gallons, for an average mpg of 30.2; although the figure is
still fluctuating a bit as the mileage isn't really long enough - all I can
honestly say at the moment is that it's doing something between about 30 and
32.  which is probably accurate enough for most purposes, at that, but since
the data are easily acquired and processed I may as well continue.  In this
vehicle, the attitude of the vehicle when filling can make quite a
difference to the amount of fuel put in.

If anyone wants a copy of the spreadsheet I use to channel all the vehicle
running costs down into a single "pence per mile" figure, let me know.  It
covers everything that gets used up per mile, including service items,
tyres, fuel, etc.  Doesn't cover standing costs, viz. the things you have to
pay even if you never drive it but have it available for use, e.g.
insurance, tax, MOT.

Aerodynamics - it's as simple as that!

Richard

The transfer box gearing is quite a lot different, 5th on the Defender is
similar to 4th on the Disco.

Martin

Nope, checked that.  My defender has a Fearns intercooler upgrade, but
I wouldn't have thought it makes much difference, and I have a light
right foot.  My defender also has a rag top although with all the
recovery gear I have in the back (or had) I'd have thought any weight
advantage over a normal defender is lost.

Yes, Nige, U.S. Gallons.

On a similar subject, has anyone heard of filling your tyres with
Nitrogen?  My local tyre place is offering it for free with new
tyres if you bother to ask them.  The poster on the wall seems to
suggest a number of benefits - was going to ask them to do it (since
it was free!) but forgot when they put my tyres on.  Anyone tried it,
or got any opinions?

Matt

which Pirellis?  I had STs on a disco, gripped the road nicely but wore out
fairly quick.  however, they're not the most expensive, either.