I must admit I can’t see how you can use less revs to maintain the same speed when you’re at maximum torque and presumably the torque converter is locked up?

I don't understand this apparent alteration in gearing.

At this speed the lockup clutch should be fully engaged, therefore unless this unit is faulty, the road speed is directly governed by the engine RPM and the mechanical gearing of the autobox.

Also I have yet to see more than 40mpg appear on my average MPG readout on my SD4, no matter how I drive there seems to be a limit about there.

PS just thought - is this RPM difference between driving in Sport (5th) and Normal (6th) ? FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 76k+ miles) (MY2015)

GundogSD4 wrote:

The car uses less rpm to carry the same speed.

Gearing is fixed, and cannot be altered electronically

My Sd4 read 53.6mpg at an average speed of 58mph, over a distance of 34 miles

Its had the gearbox flushed, latest firmware installed, Alive remap, cambelt replaced (during which it was discovered the timing was out a bit) a new intercooler and hose (as they were both leaking) serviced 500 miles previous, and using an engine friction reducer and injector cleaner

I'm happy that engine runs as close to 100% as possible
And, seeing its my courtesy car, many people comment on how smooth it drives, even at 127k miles

The apparent difference in rpm is actually 5th and 6th gear, wherever Gundog does his comparison must be on an incline, it will do 75 in 5th, the extra torque allows the gearbox to use 6th gear, it would be more obvious with a manual box. my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

Now that makes sense although of course if Alex_Pescaru’s modified instrument panel software was installed it would show which gear the box was in.

While driving the return journey from having the remap installed the car sat at 75mph and 1800rpm, prior to the remap 75mph would be around 2000rpm, I drove there and back using the exact same route of 45 miles which consisted mostly of A303 with very light traffic. 94 Disco 300 TDI Gone
96 Defender 300 TDI Gone...Should have kept it.
2003 Freelander ES TD4 Gone
2002 Defender TD5 Gone
2005 Freelander HSE TD4 Gone
2015 Freelander 2 Metropolis Keeping for now!

Are you really saying that you believe the remap altered the gearing?

No I am not saying that but the facts remain the same regarding the drop in rpm. 94 Disco 300 TDI Gone
96 Defender 300 TDI Gone...Should have kept it.
2003 Freelander ES TD4 Gone
2002 Defender TD5 Gone
2005 Freelander HSE TD4 Gone
2015 Freelander 2 Metropolis Keeping for now!

Dartman the one has the answer above.

GundogSD4 wrote:

The extra torque gives 75mph at 1800rpm instead of 2000rpm and gets 35-37 mpg but no real improvement when driven locally but it all depends how heavy your right foot is
And a cleaner engine without the poxy EGR valve.

What do insurance companies say about chipping to improve performance, and how does deleting the EGR affect the MOT?

Clearly improved performance, no matter how wisely it is used, may increase the insurance assessed risk, and if the EGR is deleted then the vehicle is not as manufactured and as I understand this may invalidate the MOT requirements.

J

Correct on both counts

HOWEVER

Its only an MOT fail if the vehicle fails its smoke test, or the emissions system has been obviously tampered with...

WRT the insurance issue, I've declared remaps to insurance companies in the past(before I had a trade policy)
If you've had an "Eco" map carried out, they tend not to increase the premium
Same for a map "Optimised for towing"