I have rules myself out only because I have always gotten exceptional gas mileage from any truck I owned.

2007 frontier averaged 24mpg v6 4.0l 250 ish hp
1997 4runner 6" lift 33" tires 19 mpg v6 3.4l 185 hp
1998 discovery all stock no airdam 14mpg v8 4.0 185hp.

I do mostly highway driving
Always use premium
tires stock and proper pressure.
Use cruisecontroll excessively
No cargo
no heavy accelerating, like this thing could if it tried.
Never speed
often drive 5mph under when highways aren't busy.

Now it could use a tune up, new plugs and wires and lube, but I did this with my 200k 4runner changed every possible thing on that truck and all fluids to synthetic with no difference. I'm going to do that to this truck but with limited funds at the moment I'm in no rush. It does have new air filter and fuel filter.

Also my 4runner did 70mph at 2000rpms this discovery does 70 at 2.4k
lower gearing? Is this normal? I figured with a bigger v8 it would do less, but they are the same horse power.

Well I guess this truck is awd, there's a difference.

Does this seem normal? Could something be mechanically wrong?

 

The mechanical reason for bad gas mileage is a heavy truck, smaller V8, brick like aerodynamics, old engine design etc. You are getting about as much MPGs as you you are going to get. Sure a tuneup will help but you will probably not see the difference. You can up the pressure in the tires to 45 psi or so but even then not sure you will see a difference.

 

Id be smiling ear to ear if I got 14mpg out of mine. But I never drive highway and theres not a flat level area for miles away. Id say give it a good tune up itsure isnt going to hurt anything. If it helps im getting about 9mpg on average

 

a good tune up sure wouldn't hurt anything...but you are never going to get great mileage with one of these. I get between 15 and 18 mpg depending on how hard I happen to drive it.

 

you said it yourself. you need a tune up. also when was the last time your O2's were replaced? throttle body cleaned? induction cleaning?

 

X2 on the O2's.... I was getting about 200 miles per tank, but after replacing the O2's, just recently, i'm getting right over 300 miles per tank, thats a HUGE difference in my book!

Just my 2 cents.

Regards,

 

Spencer - Have you checked for things like a frozen caliper and that your parking brake is releasing? Other than that and the tune-up that you know you need, welcome to LR's. It aint about fuel economy, its about going anywhere in style and comfort.

 

I would assume you had O2 sensor problems though to go from 8mpg to 12mpg.

 

14 mpg isn't awful for a Rover, but if you are doing a lot of highway driving you should probably be seeing some higher numbers. 18 mpg is the best I've ever gotten in my DII, that was almost 90% highway driving, and after adding this puppy...

http://yhst-19807630266082.stores.ya...aver--fs1.html

If you're tight on $$$ go to Autozone, they are running a special on 5 qts Mobil 1 oil and filter for under $35. I think it ends this week, so hurry up. Bosch was also running a mail-in rebate on all of their plugs, $1-$2 back per plug.

 

First thing you need to do is stop comparing a Disco to a Yota, not even similiar in any respect.
If you have a specific question on a Disco, give us all the information on it and what you have done so far.