I was wondering if anyone has noticed if the get a significant difference in mileage at different cruising speeds in these trucks. I always used to think that the slower the better, but then started thinking that may have been true with vehicles 20 years ago when the max speed was 55 and cars were heavier, less power, lower gearing etc...So, in my previous vehicle that I used to try to keep around 70 on long trips, I noticed I got almost 4 mpg better by criusing at 80. Over 80 and it would go down a bit. I will be making frequent 3.5 hour trips so I'm curious.

 

I have a '97 D1 and I set the cruise at 65mph and get 22mpg with the A/C on and window's up and 24mpg with the A/C off and windows up.
That is with the tires at 35 psi, a good alingment and the wife, three kids,stroller, pack-n-play and a diaper bagin the truck.

 

Good question!

When I first got my Disco a few weeks ago, I drove it like a nervous granny,real light-footed, mixed city/highway/rural twisty, 55-60 on the freeway and never using "Sport Mode".My first tank of gas returned 10.75 mpg...not so hot [&o]
Then I started driving about 70 on the freeway, setting the tranny in 3rd around town and using Sport Mode whenever I wanted to pass, climb or deal with the twisty rural road I drive onto work every day. The result: 12.72mpg

Then IInstalled new tires and changed the oil with full synthetic, and so Iwas expecting an even better return (my driving routes were basically the same) - 12.3mpg...little dissapointed with that. So yeah, if I need start driving faster to get me up around 14mpg thats fine with me.

Currently I'm running about 150miles to a 1/2 tank and this will be my best run yet. But that's mainly because it was mostly freeway and I was doing about 70-75mph.

 

That's incredible!!!

Are the 4.0s that much better on gas than the 4.6s? Are you driving exclusively on the freeway?

Funny thing about my cruise control; Constantly hunting up and down with the throttle trying to maintain the set speed, and that's even on a level surface...not as smooth as my Grand Cherokee. So I've been tending not to use it much thinking that it was going to guzzle the fuel gassing up and down like that all the time. Maybe it's not operating properly?

 

Ha, that's my situation. Wife, kids, pack-n-play, etc... 10% adult stuff, 90% baby stuff, going to see the grandparents as much as possible. Yeah Fonzie, I felt like a real doof trying to keep it slow in our old pathfinder for so long, meanwhile the baby is screaming...that's what made me try about 80-85 along the thruway and I was amazed at the difference. Maybe it's time for the gov-ment to raise the speed limit to 75 given gas prices and car performance these days.

 

That mpg is on trips that are all highway. The 4.6 is much better on gas because it doesnt have to work as hard.
I get 10-14mpg day to day. All depends on the traffic. I use all syntheics and premium gas. The key is to keep as steady a speed as possible, anticipate the stop lights, coast (foot of the gas) when possible and no jack rabbit starts.
The faster you go the more wind resistance, the greater the rolling resistance of the tires and the more rpm of the engine AND the engine has to work harder to overcome all of these factors.
To slow and you are below the power curve of the engine and the more gas is needed to compinsate for the lack of power.

 

Traveling with the cruise on 75 from Michigan to MD (550miles) I got 16.5-17.5mpg. Im running 18" NIttos with 32psi tire pressure. Oh yeah... not in sport mode!

 

I just completed 75% of the to-do list on my 4.6L 2003 Disco (98k).

Correct improperly installed leaking Valve Covers
Correct improperly installed intake manifold
New 8.5 Magnecore wires
New Bosch Platinum +4 sparkplugs
ATF flush / 800 miles
Mobile 1 synthetic 10- 40 high mileage with K&N filter
Techron fuel injector cleaner
Seafoam induction cleaning
Mobile 1 synthetic both gear and transfer
Lubed U-joints

+70% Of my driving time is spent with a heavy cargo trailer in tow. Before I started the list I was consistently getting 10.5 mpg. I’ve since burned two full tanks of 91 and calculate a happy 16.9mpg and 17.1mpg !!!!! Haven’t done a trip with out the rig behind me but it sure was nice to see the odometer roll past 365.

As for speed, I’m generally stuck in the right lane. 55-65mph with the big trucks.

Fonzie: I’m surprised to read 12.3 mpg. Since my driving load is not typical of Land Rovers and my mileage is so high. I definitely baby my engine and drive train - consciously keeping the RPMs low or high as needed.

Fonzie: I know that my gas gauge is not accurate to the scale. The ½ tank mark is really like 3/8sof a tank. Ok by me, I’d rather have precision at the bottom of the scale vs the top. Is your fuel gauge accurate to the scale? And congratulations on the new truck

As for the cruise control: Mine oscillates only for the first 20-40 seconds as the computer learns the road and then smoothes out perfectly.


MWmG

 

No, it's like yours; When it says I have 1/2 tank left it's more like 3/8. When I say 150miles at 1/2 tank, I mean that's the most my trip meter has shown by the time the gauge showed 1/2 tank on the scale.

Sounds like the reason I'm not getting as good mpg as you guys is because my driving is very mixed with freeway amounting to just 1/3rd or less, whereas you guys are doing a lot of freeway time. But 17.1mpg is an impressive return for towing a big heavy trailer. I'm planning on changing out all my driveline lubes for synthetics here pretty soon...maybe that will be worth an extra mile. And maybe I should consider replacing my plug leads for Magnacores? Although I only have 34k miles the leads are 4yrs old now. Also, I'm pretty sure my plugs are the originals, since the truck has been maintained by the dealer from new, following the LR maintenance schedule, which doesn't require replacements till the 60K service. Unless I go by the 48month time requirement, in which case they are now due to be replaced.

That's interesting! I didn't know the cruise control had that feature. I'll check it again and give it a chance to settle down. Thanks for that!

 

Strange, I seemed to get 19l/100km both ways on a trip this weekend, and one way had a severe headwind. I was sure I'd get better on the way back.