I was just wondering wether at a steady 70mph (cruise control) for a couple of hundred miles I should expect better than the 30mpg that I got. I have to admit to using the cars tripometer ( is that a word?) and I’m not really bothered about the actual expense but more worried that something may be amiss with the car. Interested to hear other experiences, I probably need to confirm with a brim to brim test and also without cruise control. Geoff

i should think you should Geoff...i reckon it should be in the high 30's.

i find the 'sweet spot' in my tdv6 is around 65'ish which results in low 40's mpg..



i did get this the other day,

 ... - .- -.




Y. O. L. O.
.

Does aerodynamics play a part, I did have a mountain bike and rack on the back. Geoff

On a steady run down the motorway the other week, I saw 38 mpg. Speed was between 65 to 80 mph.

HTH
Ivan 2013 Vogue SE SDV8
2013 Freelander 2 SD4 HSE Luxury

Very much so... LR tested the expedition rack and on its own that increases drag by 15%, IIRC just the cross bars increased it by 4%

I may have to check again - this time no bike, no cruise and brim to brim. Geoff

Sorry to be the bearer of bad news, but.....

The "lieometer" on your car readout is at least 3-4mpg optimistic I'm afraid!

If you want to know the true mpg you need something like the "Road Trip" app (which is free), and will tell you exactly what your car does. My MHEW D300 is averaging 34mpg, which includes a lot of under 10 mile trips, and am very pleased with that on a 2.5 tonne car  All LR cars from 1984
2021.5 Vogue SE D300 Carpathian Grey
2018 Vogue SE British Racing Green GONE

I found the cruise control eats fuel.

Let’s say it’s the way I drive & get that bogeyman out of the way.

Firstly long hills , I’m happy to slow down a bit going up a very steep long hill rather than hitting the accelerator, cruise maintains a speed regardless of cost/mpg . France has many of those steep hills on my journey. Just a mile from our village is a two mile hill!!!!! ;

Overtaking:

Using foot control , I tend to get fairly close to a car before pulling out, let’s say the two second gap. Hard to specify, just seems natural.

The trouble on cruise control is, cruise control is picking up a car in front at least 100 m or more ahead, guessing 4-5 seconds.
Thinks there is a car, the car very gently eases off the gas, I hardly notice, when I do notice I’m closing in the car in front but the speed may of dropped 10 mph. ‘
Pull out to overtake …. Car thinks it’s an open road and immediately hits the gas, pushes the revs up from the steady 1500’s to 2,000 and a great lurch forward.

Of course the answer is to pull out long before I need to do so, when the little light comes on , way way to early. In France that’s bad driving, here it’s just hogging.

I find my foot give much superior MPG. My guess is 2-3 mpg better with the foot. I only use cruise control on a long journey and want to have a semi break, or if it’s an average speed check area.

A long run a few months ago & constrained in the U.K. to 50 mph I was in the mid high 30mpg from memory 36/37 mpg. This was flat ,not busy no significant hills & a lot of cruise control that worked due to light traffic.
Normally I expect At 70 mph it’s 31 mpg
At 80 it’s 29 mpg
At 90 + in a hurry for the ferry it’s 27 mpg
That’s with the 2016 405 4,4L diesel , Which was about 3-4 mpg better than the 2012 Westie 4L

In the end, I can’t worry about the extra £10.00 it costs to crack on and tend to move along to suit my timetable. 80-90mph in france. 70mph (I wish) in the U.K.

Now I have the new 300D , no long runs yet, but expecting a significant improvement. Expect no change with cruise control. Filters are in fact so good that in certain circumstances, when the ambient air is already polluted, a diesel car will tend to extract more particles from the air than it emits. Emissions Analytics worked with........etc etc

He who dies with the most toys wins...

Bill

My 2018 3litre was averaging around 27mpg doing exactly the same mix of driving so the latest D300 is much, much better  All LR cars from 1984
2021.5 Vogue SE D300 Carpathian Grey
2018 Vogue SE British Racing Green GONE

A long run a few months ago & constrained in the U.K. to 50 mph I was in the mid high 30mpg from memory 36/37 mpg. This was flat ,not busy no significant hills & a lot of cruise control that worked due to light traffic.
Normally I expect At 70 mph it’s 31 mpg


Thanks Bill
My mind is at rest actually it has been for years. Geoff

Have to say I rarely see much above 32ish on typical UK long journeys, we came back from Snowdonia today (150ish miles) and managed 32mpg on the computer, although we did have a good run out from Chelsea to Nottingham and managed 36.5mpg on the computer in light traffic a few weeks back.

For a while I tracked it on an app, but it was only 1/2mpg out from the car's computer, so now I don't bother.

When choosing the L405 we had a couple of lengthy test drives from the dealer in a TDV6 and SDV8 and the V6 was significantly better on longer runs. Sold - Bell a 2015 MY16 Loire Blue Autobiography 4.4 SDV8
Previously George a 2007 MY07 Java Black VSE 3.6 TDV8
Previously a 04 MY04 Defender 90

Last edited by TJH1985 on 1st Sep 2022 10:19am. Edited 1 time in total

I’m going to Longleat next Thursday and coming back Saturday so it’s my chance to check things out - no bike rack, no cruise control but I will use the cars computer because even if it is wrong it will show the improvement (if any) I probably will still be aiming for around 70mph. I hope the monkeys don’t do too much damage and it’s the last time I allow SWMBO watch Animal Park  Geoff

I have just check some of my long drives in Germany with a bike rack on tow bar…

With 4 mountain bikes: average 70mph over 160miles I got 30mpg… was the same on other parts of that trip

With a box on the bike rack (snowboarding)
Average 60mph over 120miles I got 31mpg

The time I have used the bike rack in all the different trips 28-32 mpg…

Without rack:
Average 62mph over 277miles I got 35mpg SDV8 AB MY 2020
MINI Cooper S Cabrio
Kit: Jaguar XK140 (in progress - the website is link to build)

This is in a SDV8 with Cruise control.. SDV8 AB MY 2020
MINI Cooper S Cabrio
Kit: Jaguar XK140 (in progress - the website is link to build)

I absolutely agree with the comments about adaptive cruise control, it appears rather dim witted compared with some other systems often resulting in my experience in hard acceleration when it senses a clear road having slowed for a perceived obstruction ahead.

The readout is certainly optimistic- I’ve checked in against full to full tank manual calculations and it’s been between 2-4mpg out.

I’ve found that a steady 60-65 mph, lifting off and gently reapplying power has given the best results on the motorway but it’s a bit frustrating and 70 mph is not much different. Obviously the aerodynamics play a part, and the weight plays a major role in overcoming mass when pulling away from stationary and on hills. Anticipating traffic lights to minimise coming to a complete stop seems to help. However, I’m never getting more than around 27-28 mpg around town but have averaged 32 mpg over the last 7,000 miles. In my experience 36-38 mpg is feasible on A roads, but only when using extreme restraint!

Click image to enlarge